You are given a text that consists of multiple sentences. Your task is to perform abstractive summarization on this text. Use your understanding of the content to express the main ideas and crucial details in a shorter, coherent, and natural sounding text. 
Text: As we look back on the past year, I feel that 2020 was a proven ground for our company.
It gave us the opportunity to prove the resiliency of our business model and the disciplines we've engineered for more than a decade: things like capital management, cost management, operational agility and the willingness of our team to embrace change.
We've demonstrated these capabilities during choppy periods in the past, but last year wasn't just a downturn, it was a sharp and significant economic disruption.
And we stood up to those conditions while keeping our people safe, streamlining our operating costs, aggressively flexing our capex and managing our excess capital to reduce leverage.
In addition, we kept our full year adjusted EBITDA margin to within 50 basis points of 2019, despite significantly lower market demand, and we generated record free cash flow.
And now, things are getting better.
Most of our end markets have been on a steady path to recovery since the third quarter, and we saw that continue in Q4.
These factors help us narrow the gap in rental revenue year-over-year from being down over 13% in Q3 to down just 10% in Q4.
And as you saw yesterday, our fourth quarter results were better than our guidance for total revenue, adjusted EBITDA and free cash flow.
I was also pleased that throughout 2020, we stayed laser-focused on execution, while remaining flexible and agile in a very fluid environment.
And most importantly, we never wavered from our fierce determination to take great care of our employees and our customers.
We didn't resort to reactive cuts in our service capacity that would harm our customer service or slow us down in the upcycle or impact our long-term earnings power.
Early on, we committed to keeping the key in the ignition on capacity so we could start the engine up at any time.
And as we enter '21, this has proven to be the right decision.
The execution of that decision rests squarely with our people, and they have consistently delivered.
They're the reason why our safety reportable rate remained below one for all four quarters of 2020.
And it's a credit to their professionalism that our COVID protocols were adopted so quickly companywide, allowing us to serve our customers safely.
And the financial results you saw yesterday were generated by the talent and commitment of our people all working together as one UR.
It's an exceptional team, and I'm very proud to work beside them.
Now let's look forward to the current year.
COVID isn't a traditional cycle, but it's a cycle nonetheless.
And we believe it will continue to have an impact for the foreseeable future.
As our guidance indicates, we'll continue to gain ground in '21 as we work our way back toward pre-COVID levels.
Our sentiment echos the majority of our customers in our recent surveys, the comments we hear from the field and other external data points we've collected.
We're optimistic of the year, while being realistic that visibility is still somewhat limited.
What our guidance doesn't show is the cadence of demand this year.
But once we lapped the first quarter, our toughest comp will be behind us, and then we expect to return to growth as we move through '21.
And we base this on a couple of factors.
The recent spike in COVID cases is projected to settle down in the coming months, which should help reactivate some projects that were temporarily halted.
And as the vaccines are rolled out, business confidence should continue to improve.
And this will provide a tailwind for both capital projects and MRO spending.
And as demand trends up, we're well positioned to be first call for our customers.
And before I get into our operating environment, I want to mention our fourth quarter revenue from used equipment sales.
It was $275 million, almost 13% higher than prior year, and it was driven by healthy retail demand.
And as you know, we look at the strength of the used equipment market as a key indicator for the rental industry.
And when the retail market is favorable, it tells us that contractors are projecting needs for that fleet.
Another positive indicator is that our industry overall showed great discipline on the supply side in 2020, and this is a good place to be as activity ramps up.
Looking at our operating environment, there are some encouraging signs.
The verticals we called out as most resilient on our last call are continuing to lead project activity in markets like power, healthcare, distribution and technology.
Within these verticals, we're looking at a range of jobs, including data centers, hospitals, warehouses and even power plants.
And on the other side of the ledger, petrochem continued to be soft in the fourth quarter.
The good news is that we're seeing light at the end of the COVID tunnel, and we expect this sector to do better this year led by scheduled turnaround activity in downstream and chemical process.
Within non-res, which is our largest revenue base, a number of new projects broke put ground in the fourth quarter and others plan to start up this year.
These include some big stadium projects that were postponed when COVID hit.
And the same is true of airport construction and renovation.
We see a number of these multiyear projects back on the table.
And to a lesser degree, road and bridge work, which generally has remained steady.
Infrastructure has been topical since the election.
And while the details and the timing are unknown at this point, President Biden has been clear that this will be a priority for his administration.
And as the economy continues to heal, United Rentals is in a strong position to benefit from any increase in end market spending, including infrastructure.
And we've invested for years in positioning the company for this type of scenario.
Our specialty segment had another good quarter, led by our power and HVAC business, which generated fourth quarter same-store revenue that was higher than the prior year.
It underscores the importance of our ongoing investments in specialty operations.
In total, we plan to open another 30 specialty cold starts this year, which is double the number that we opened last year.
And this will bring us close to 400 specialty locations by December.
You may recall our mantra that figure doesn't really matter unless we're constantly driving for better.
And the way we get there is by doing what we say we're going to do.
2020 did its best to challenges on that, but we came through for all of our stakeholders, and the learnings we gained from that experience have been incorporated into our operations.
And we'll leverage these learnings as we return to growth.
Finally, we said we would fulfill our responsibility to investors by protecting the long-term earnings power of the business, and we're doing that, too.
The takeaway from 2020 isn't what went wrong in the external environment, it's what went right when we committed to a course of action and met our goals.
Yesterday, you saw the results of that commitment.
And today, we're telling you that we intend to deliver again in '21.
So I'll stop here and ask Jess to take you through the numbers, and then we'll go to Q&A.
So Jess, over to you.
Our financial results in the fourth quarter were better than we expected, with rental volumes continuing to recover and strong used sales activity at retail, and more on both in a minute.
Costs were in line and supported by -- supported solid margins in the quarter.
Free cash flow for the year also exceeded expectations, and our leverage at year-end was down versus 2019.
That's all good news as we move into 2021.
I'll provide some color on our '21 guidance before we get to Q&A.
Let's start now with the results for the quarter.
Rental revenue for the fourth quarter was $1.85 billion, which was lower by $208 million or 10.1% year-over-year.
Within rental revenue, OER decreased $190 million or 10.9%.
In that, a 5.6% decline in the average size of the fleet was a $98 million headwind to revenue.
Inflation of 1.5% cost us another $25 million, and fleet productivity was down 3.8% or a $67 million impact.
Sequentially, fleet productivity improved by a healthy 420 basis points, mainly from better fleet absorption.
Rounding out the decline in rental revenue for the quarter was $18 million in lower ancillary and rerent revenues.
As I mentioned earlier, used equipment sales were stronger-than-expected in the quarter, coming in at $275 million.
That's an increase of $31 million or about 13% year-over-year, driven almost entirely by an increase in retail sales.
That reflected OEC sold up 35% year-over-year in the retail channel for the second quarter in a row.
Used margins in the quarter were solid at 42.5%.
Notably, these results in use reflect our selling over seven-year-old fleet at just shy of 50% of original cost.
Let's move to EBITDA.
Adjusted EBITDA for the quarter was just under $1.04 billion, a decline of $117 million or 10.1% year-over-year.
The dollar change includes a $143 million headwind from rental.
And in that, OER made up $140 million and ancillary and rerent together were the remaining $3 million.
Used sales were a tailwind to adjusted EBITDA of $11 million, which offset a $3 million headwind from our other non-rental lines of business.
And SG&A was another benefit in the quarter of $18 million, with the majority of that help coming from lower discretionary costs, mainly T&E.
Our adjusted EBITDA margin in the quarter was 45.5%, down 150 basis points year-over-year, and flow-through as reported was about 66%.
I'll mention two items to consider in those numbers.
First, used sales made up a greater portion of our revenue this quarter, which was a headwind to margin and flow-through.
Second, I mentioned on our Q3 call, back in October, that we had a benefit in bonus expense in Q4 2019 that would cause a drag this Q4.
Adjusting for those two items implies a margin of 46.1% and flow-through for the quarter of just over 56%.
Both results were largely as expected and pointed to continuing cost discipline even as certain operating costs started to normalize.
A quick comment on adjusted EPS, which was $5.04 That compares with $5.60 in Q4 last year.
The year-over-year decline is primarily due to lower net income from lower revenue.
Let's move to capex.
For the quarter, rental capex was $176 million, bringing our full year spend to $961 million in gross rental capex, which was 55% less than what we spent in 2019.
Proceeds in 2020 from used equipment sales were $858 million, resulting in net capex of $103 million.
ROIC remained strong at year-end, coming in at 8.9%.
That continues to meaningfully exceed our weighted average cost of capital, which currently runs about 7%.
Year-over-year, ROIC was lower by 150 basis points, primarily due to the decline in revenue.
Turning to free cash flow, which was a record for us at over $2.4 billion in 2020.
This represents an increase of over $860 million versus 2019.
As we look at the balance sheet, our having dedicated the majority of our free cash flow to debt reduction in 2020 resulted in a $1.9 billion or almost 17% decrease year-over-year in net debt.
Leverage was 2.4 times at year-end, down from 2.6 times at the end of 2019.
Liquidity remains extremely strong.
We finished 2020 with just under $3.1 billion in total liquidity.
That's made up of ABL capacity of just over $2.7 billion and availability on our AR facility of $166 million.
We also had $202 million in cash.
Our view to total revenue includes a return to growth in rental revenue with the season, starting in April.
We look forward to getting past the challenging comp in Q1 as we lapped the start of the pandemic and move to delivering rental growth for the rest of the year.
Our guidance includes a range of outcomes given our seasonal patterns and assumptions we've made on the pace of continuing recovery across our end markets.
We're planning for another strong year in used sales, and we'll look to increase our capex spend to replace that fleet.
Within our guidance, that reflects over $1.9 billion in replacement capex.
Beyond that, we continue to be focused on absorbing the fleet we own, and we'll adjust our growth capital accordingly with total spend planned at pre-COVID levels.
Our range on adjusted EBITDA considers not only the volume growth we expect in revenue, but also our continuing to manage costs tightly.
We'll leverage what we've learned in 2020 using our own capacity to support our customers with less reliance on third-parties.
As our business continues to recover, we'll also see a reset of costs that ran low in 2020, such as T&E and bonuses.
Finally, one of the best indicators of the strength of our business model is the resiliency of our cash flow, especially as we invest behind growth.
In 2021, we expect another year of generating significant free cash flow, and that's after considering a return to over $2 billion in capex spending.
We'll continue to use our free cash flow to pay down debt and reduce our leverage.
Operator, would you please open the line?

user
anticipate another robust year of free cash flow generation, after significantly increasing our capex to support growing demand.
rental revenue for q4 was $1.854 billion, reflecting a decrease of 10.1% year-over-year.

assistant