OS MAX 50SX-H Ring including pipe - New Unboxed (32)The best '50 class' Heli engine on the market! That CNC machined cylinder head has been developed to give better power and improved cooling at the same time. The new carburettor has also been improved 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 and is fast becoming the best seller as well. It's an OS,