... 2.ISO/TS16949:2002 3.Longlife,good after service Piston ring set for Caterpillar 3304(auto parts) 1.Casting ... casting iron, ductile iron rings;keystone ring, taper ring, drum ring;Chroming ring, spray molybdenum ring.Capacity:40 Millions Pcs/year.2. ... the barrel surface ring,keystone surface ring,cone surface ring,twist side ring,chromium plating ring,spray molybdenum ring,nitride ring,steel disc rng ...