Rings are hard and brittle and will easily break if bent beyond that necessary to ease them into the piston groove. Noting the ring locating pin and arrow on the piston top in the other posts, insert the piston into the sleeve up to the ring. Tighten a cable tie or a hose clamp around the ring, compressing it and allowing, then, the piston/ring to be gently tapped into the sleeve. Tighten the table tie or clamp just enough to compress the ring, but still allow the piston to slide out into the sleeve.