4mm scale outside crank set including 00 axle for Romford/Markits driving wheels. Machined in stainless steel, any Romford or Markits driving wheel can be used. The crank axle has a machined square end onto which fits the crank arm with a machined square hole. Locked in place with a flanged screw. No soldering rquired. Markits mini screwdrivers needed for assembly. GWR pattern crank.