Brand new Aerotek Hi- Performance 503 Rotax top end Re Ring kit for std bore engines. Includes the following:  

1. Piston rings for 2 std 72.00 mm bore dual ring pistons. 

2. Top end gasket set.

 These kits are design to and will replace your oem parts perfectly. A/P A/I recommended. Hypereutectic pistons are made of an aluminum alloy which has much more silicon present than is soluble in aluminum at the operating temperature. Hypereutectic aluminum has a lower coefficient of thermal expansion. 

NOTE We carry sets for any oversize bore. .010, .020". .040. 1st  2nd  4th oversize are available plus Rotax 277 377 447 503 532 464 521 582 kits. I