OO9/009 B11-109SC V2 Adapter Including Compatible Chassis for KATO 11-109/11-103
£36.05
The adapted chassis body is 50mm long + fixed OO9 hook couplings (making 57mm over couplings) compared with the Kato at 54mm (without couplings). This certainly includes all of mine (which include their own couplings anyway).
