Hello All, I compensated for the DL 50 ring purchased from me by sending another ring for one of the customers other engine. I feel that with too much difference between worn piston & new cylinder my flat face rings will never seal as I tried to explain to customer. With tighter tolerances my ring will work but loose tolerances a ring with rounded edges and larger pre load gap to apply more tension on cylinder would be better. But there will be more heat involved with higher tension rings and round edges on rings will allow more blowby. Take Care & good flying, fishing too.