by the Stockholm Commuter Rail Pendeltåg to Arlanda Airport, or crossing the county border to Uppsala and Knivsta, incur additional costs. As mentioned above, the additional cost for using the railway station at Arlanda airport is 120 SEK (can be paid either upon arrival, or in advance - then it needs to be used within 2 hours!). Travelling to Uppsala or Knivsta with SL from Stockholm County requires a valid Uppsala County (UL) ticket in addition to the usual SL ticket. Note: Applies to SL Stockholm Commuter Rail (Pendeltåg) train only. Other operators have their own tickets including Arlanda Express. (SL Stockholm Commuter Rail (Pendeltåg) as well as National and Regional trains stop at Arlanda Central Station (Arlanda C) while Arlanda Express stops at Arlanda South (first stop): Terminal 2, 3 and 4 and Arlanda North (second and last stop): Terminal 5.) SL's ticket prices The prices for the most common tickets are as follows. The discounted fare is for persons under the age of 20, or over the age of 65. Archipelago boats Archipelago boat traffic is administered by Waxholmsbolaget. Until 29 April 2022, SL tickets that are valid for at least 30 days (30-day, 90-day, and annual travel cards) are also acceptable. It is also possible to pay with SL card credit. The price of ticket depends on length of the journey. Discounted fare is applicable for children under 19, students, and persons 65+. It is possible to buy a return ticket, but the price is the same as for two single journey tickets. Ö-card is for residents only. Arlanda Express tickets The Arlanda Express train between Stockholm central station and Arlanda airport has its own relatively expensive tickets or travel cards for exact number of journeys. Tickets can be bought in vending machines near the platform, or electronic tickets on the internet. Tickets are valid for 90 days. Children under 18 years travel for free when accompanied by an adult. Flygbussarna Flygbussarna provides transportation to four airports in Stockholm. Below are listed prices when tickets are bought online/via app. Adult and youth tickets are up to 20 SEK more expensive when bought by other ways. Contractors The contractors used by SL are as of July 2019 the following: VR Sverige Bus traffic in Ekerö, Sollentuna, Solna, Sundbyberg and Västerort. Rail traffic on Saltsjöbanan, Nockebybanan and Tvärbanan. Keolis Bus traffic in Stockholm City Centre, Botkyrka, Huddinge, Lidingö, Nacka,