Each car features fifteen compartments, which can each be utilized with a single or twin bunk configuration.

The carriages have a unique octagonal shape, are 27 meters (88 ft 7 in) long and weigh 48 tonnes.

The first phase looked at market demands and costs, and concluded that the new sleepers should be built exclusively as twin-berthed cabins.

The only significant operating fault with the carriages was the freezing of the water system during cold spells.

[1] Ahead of the 1994 Winter Olympics in Lillehammer, NSB decided to build a new royal coach.

NSB also changed its policy, so for a fixed fee passengers could book the entire compartment.

To provide comparability with older WLAB and B5 carriages, WLAB2s were initially installed without a closed gangway connection.

On the corridor side there are two rows of windows and fifteen folding seats, each with place for two people.

[1] The closest compartment to the doors is slightly larger than the others, allowing for enough space for a wheelchair to access it.

On the reverse wall of the beds are three niches, two which can be used as a wardrobe and one which features a folding ladder to the upper bunk.

[1] At each end of the carriage is a toilet operated with a vacuum sewer system, identical to those install on B7 and Class 92 trains.

At the exits there are supplementary heating which allow for individual regulation of the room temperature between 12 and 22 °C (54 and 72 °F).