12mm "circlip" for original Vespa V50 and PK 50 S-XL2 pistons (from 50cc to 115cc).
There are two common methods for securing a piston pin, which depend on the piston's groove, which can be square or round. The original Piaggio piston has a square-machined locking groove and is secured with a square circlip.
Tuning cylinders from DR, Polini, Malossi, etc., typically have a round cutout. Their piston pin is secured with a round piston clip.
Circlips should be mounted / dismounted with a circlip plier.
Note: The long-stroke cylinders PK 80 / 100 / 125 require the larger circlip with a 15mm diameter.
