This is the 4000kV Pro4 Brushless Short Course Motor from Tekin. FEATURES: 4 pole 12 slot high torque design High RPM ABEC5 oversized bearings CMC machined 6061 T6 billet aluminum heatsink can Neodymium sintered magnets Designed to handle 2s LiPo batteries Dual plug sensor wire harness for use with all sensored and sensorless systems High purity copper windings for greatest efficiency INCLUDES: 4000kV Pro4 Brushless Short Course Motor with Sensor Wire REQUIRES: Electronic speed control such as the Tekin RX8, TEKM2300 SPECS: Weight: 6.75oz (193g) Shaft Dimensions: .60x .196" (15.3 x 5mm) Motor Diameter: 1.4" (35.8mm) Motor Length: 2.1" (52.9mm) Bearing Dimensions: Front: 5x13x4mm / Rear: 5x10x5 Turns: 2D jxs 09/21/11 ir/jxs