Uses Slaters 10mm coach wheels S9121. Slaters bearings used in solebar and pivoting piece. Centre wheelset needs a slotted bearing 1/8" wide, 3.2mm deep and 10mm dia with a short 1.6mm spigot of 6.3mm diameter to locate in the solebar and fixed with superglue or epoxy. 1/16 stainless rod connects the two Slaters coupling hooks (G9026) and also acts as the pivot for the compensated wheels. 