This kit is the BR SB Flatrol 20 Ton Trolley and is the same model as the preserved wagon at the Bluebell Railway. The kit comes with 3D printed wheels as standard and has the option of having Dapol coupling pockets and Hornby couplings added to the pack.
 
This kit has been tested with both PECO and Hornby wheels.As well this kit is compatible with Dapol N gauge NEM coupling housings which are available from different retailers. These work with any TT:120 or N gauge NEM couplings including Hornby standard TT:120 couplings.