O.S. MAX 50SX-H Ring Hyper (L-OS15550) The best 50-class engine on the market just became amazing with the introduction of the new 50SX-H Hyper. That CNC machined cylinder head has been developed to give better power & enhanced cooling at the same time. The new carburettor has also been enhanced to help extract more power than the standard engine without sacrificing the throttle precision you have come to expect from OS helicopter engines. This truly is the best engine in the 50-class & is fast becoming the best seller as well. Its an OS, what else would you expect!! Specification: Weight: 413g Bore: 22.0mm 0.866in. Stroke: 19.6mm 0.772in Power Output: 1.8/17000 (BHP/RPM) Practical RPM: 2000-20000