Polini racing full cheek crankshaft with 12 mm gudgeon pin, higher precompression and standard stroke (39.2 mm). Plastic parts are cast to keep weight down. The lower connecting rod bearing is has a copper washer. Additional hole at the gudgeon pin for improved oiling at high revs. Swap out your damaged rod but keep your Polini crankshaft. Polini quality for the race track & the demanding tuner. Caution: only to be used in conjunction with appropriate tuning kit piston with 12 mm gudgeon pin.