There is a pin in the ring groove that MUST be lined up with the gap in the ring when installing the piston in the cylinder. Pin is not unique to the DLE 20. EVERY 2 stroke engine I've ever had apart has this pin. It's there to prevent the end of the ring from snagging one of the openings in the cylinder. Noteworthy is the fact that if you force the piston into the cylinder, there's a very good chance you'll break the ring. -Al