The seats have a different cover than in the rest of the train, and there is room to place your luggage and hang your coat. To travel in First Class, you pay an additional 30 SEK per county that you travel in and 50 SEK for over the Öresund bridge. If you wish to upgrade from Second to First Class onboard, you will be given an invoice by the onboard staff.
You will find the First Class section in car 11 (and, where applicable, in cars 21 and 31). There are a total of 20 seats, whereof 10 can be reserved. From the outside you can identify the First Class section by the two yellow stripes above the windows.