I have placed Frank Boman rpiston rings in my & my friends gas engines andhis rings havethe best fit & the material is very good. Every engine ran better & smoother. I have a DA Desert Aircraft 50cc engine. The compression is good but the ring seems rather narrow as the fit in the ring grove seems to be very loose. This makes a click you can hear at the exhaust port and cansee the extra "play" the ring has in the groove as you wiggle theprop back and forth. I will most likely replace it. Capt,n