One pair of 7mm scale SR style return cranks with SKF roller bearing small end. Made in stainless steel, designed for Slaters driving wheels. Crankpin is retained by an M1.6 flanged screw at the rear. The crankpin has a machined hexagonal end over which the crank arm locates with a hexagonal cutout. Locked in place with an M1.6 flanged screw, no soldering is required. Crank arm is 12mm long. 14BA Nut Spinner needed for assembly.