This is the Great Planes ElectriFly RimFire .25 42-40-1000 Brushless Outrunner Electric Motor. FEATURES: For Sport airplanes up to 4.5lbs (2040g) and 3D airplanes up to 3lbs (1360g) Designed for explosive acceleration and maximum torque Lightened aluminum can houses high torque rare earth Neodymium magnets Double shielded bearings Virtually maintenance-free; no commutators or brushes to wear out Two year quality guarantee INCLUDES: Great Planes ElectriFly RimFire .25 42-40-1000 Brushless Outrunner Electric Motor with prop adapter (GPMQ4906), motor mount and 4.0mm connectors REQUIRES: 45A ESC, can use FlightPower 40A Brushless ESC (FPWM0230) Propeller: 10.5E-11x7E Four 3x8mm flat head machine screws SPECS: Can Diameter: 1.7" (42mm) Can Length: 1.6" (40mm) Shaft Diameter: 5mm Shaft Length: .67" (17mm) RPM/V (kV Rating): 1000 Weight: 4.4oz (125g) Propeller: 10.5E-11x7E Input Voltage: 11.1-14.5V (3-4S LiPo) Max. Constant Current: 45A Max. Surge Current: 50A Burst Watts: 740 Max. Constant Watts: 666W No Load Current: 2.5A COMMENTS: The three-number designation refers to Motor Diameter, Motor Length and kV Rating. DO NOT USE Silver Series 45A Brushless ESC (GPMM1840), problems may result. jxs 4/20/06 ir/jxs update JAW 7/6/10