Abstract: A piston ring having a "Y" cross section is received within an annular groove of a piston which is reciprocable within a cylinder. The piston ring is formed from a single strip of material with an integral inner end. Two flanges extend laterally outwardly in opposed directions from an outer edge of the central leg. An outer end of each flange is yieldably urged against the wall of the cylinder to sealing engage the piston within the cylinder and force two circumferential ends of the ring into abutting engagement. The groove includes a radially inwardly extending portion to receive the central leg portion and a "V" shaped portion with inclined walls which each underlie one of the flanges.