Ownership of the class moved to Kristiania Sporveisselskab (KSS) in 1904, when it bought KKS.

Kristiania Kommunale Sporveie was the third street tram operator in Oslo and the first to be owned by the municipality.

[2] Two city engineers were sent on a study tour of Germany and the Netherlands to gain experience from tram operations there.

[1] KKS placed its order with Schuckert & Co. of Nürnburg and Busch, consisting of twenty motor cars and twelve trailers.

Schuckert had recently delivered the first trams to Holmenkolbanen (HkB), which operated a suburban tramway in Oslo.

The lack of secondary suspension caused complaints from customers who experienced a smoother ride with the trams operated by KSS and KES.

[2] KKS started a grain tram service in 1918, which linked Statkorn's silo at Vippetangen to Bjølsen Valsemølle.

The motors, undercarriage, platforms and frame were reused, while an all-new body were built.

The units were renumbered 505–521 and received motors from Siemens Schuckertwerke, while the undercarriages were built at the depot.

The main upgrades included new connectors to allow them to run in multiple with newer trams and track brakes.

One trailer was requisitioned by the German occupation forces and moved to the Stettin Tramway.

They museum attempted to preserve a trailer, but Oslo Sporveier instead chose to scrap the last unit in December 1969.

They were 7.8 meters (26 ft) long and had a capacity for twenty passengers along two benches aligned along the width of the carriage.

[2] The modified units from 1919 received a lengthening, with longer and larger platform bays.

This allowed standing capacity to rise to 48, although the cabin and the seating remained unaltered.

The wheelbase increased to 3.0 meters (9.8 ft) and track brakes and secondary suspension was installed.

In the 1922 modification they were further extended by 1 meter (3 ft 3 in), this time the cabin was lengthened and seating increased to 24 and the platform bays were rebuilt with walls.

[2] In their final, "Municipal HaWa" configuration, the trams were 11.2 meters (37 ft) long, weighed 15.9 tonnes (15.6 long tons; 17.5 short tons) and had a power output of 102 kilowatts (137 hp).