This is the Futaba BPS-1 Engine Backplate Sensor for Gyro Governor. FEATURES: Designed for use with the Futaba GY701, CGY750 and GV-1 governors Ideal for use with the O.S. 55HZ-R and 91HZ-R heli engines Monitors and maintains RPM at a selected level Eliminates the need for fan mounted magnets and governor mounts INCLUDES: BPS-1 Engine Backplate Sensor with Instruction Sheet REQUIRES: Connecting to governor and backplate of engine SPECS: Length: 25.8" (655mm) Weight: 0.28oz (8g) jxs 08/23/11 ir/jxs