Its a nice system but putting the parts in a kit would be better because this isn't all youll need. To install a door on a trolley system you need the track, hanger brackets & roller assembly for the key components and then likely the sliding bumper, stay roller, end cap and a handle. I originally purchased enough parts to have a door system that closed in the center of the doorway and when I made the doorway smaller I had some extra parts. I never thought Id use them again but I decided it was time to expand my 2-car size garage that only had a single wide overhead door so I could actually get my Ford Expedition in for the winter. I found a used single 8 high x 7 wide solid steel door that lifted up and over the vehicle. However, though I could barely get the vehicle in the garage I couldn't walk behind it to get out of the garage. Something had to give so I decided to take the door off the rail system, remove all the overhead hardware and install the door outside the garage rather than inside and that gave me 9 more of floor space: 6 for the wall thickness, 2 for the door thickness and about another 1 for the tracks holding the door a little more inside than needed. Since my opening was 8 wide I used two 8 sections of track you can use less by setting the rollers in farther 2 at each end of the door and setting the track back on the closing side but my door weighs about 250-pounds so I wanted the rollers close to the ends for a smoother roll. With 2-sections of track you need 3 hangers at the minimum one at each end of the track and one in the center that joins them together make sure the center one has 2-setscrews on it or it won't work for joining 2-rails. The instructions call for a hanger about every two-feet but thats overkill and theres no way the rail will bend unless you're using it to roll an auto engine across it. I had to go with a larger stay roller because the 44140 allows for a 2-1/4 max door and mine is 2 so it was too tight for an easy the slide. The tracks plus the door are a lot of weight so this has to go up with lag bolts into studs or with carriage bolts and large washers into the sheathing. Once you start rolling the door open theres a lot of momentum heading toward the end of the rail so I just drilled mine out and used a lag bolt with the end cap. The rollers are enclosed from the weather so they stay lubricated and you can hang a door almost flush with the exterior wall and I used some garage door rubber side seal screwed into the door for a draft free closing. If you don't use the bumper and stay roller the door will swing out at the bottom and I added a boxed end on the closure end to keep the weather out on one end and the rail does a pretty good job on the top. The cost adds up fast with all the parts but not having a door inside the garage gave me the added space, I now have ceiling hooks over the vehicle, I don't need a garage door opened and theres no chance a spring is going to snap but this industrial look may not be aesthetic enough for some but when the hardware is painted it looks pretty sharp. Lastly, the hangers added enough additional height so that I could mount the rails right over my overhead door next to it. I did buy some parts at the home centers and their pricing was pretty good but were hard to find because they were in the back of the store with the doors & windows in one and with in the fence aisle at the other. Since this is like a giant erector set its a pass/fail so it gets 5-stras and since you cant do it with just one part Im using the same review for all the parts. Also check all the hardware variations shown on Amazon because National and Stanley are both interchangeable.