Feature:1.High torque & high efficiency. The overall efficiency exceed 90 percent.2.Low heat production， long lifetime， strong overload protection and it can function 95% of its features without any heat sink appliance.3.high quality materials adopted: high intense aluminum alloy anodizing shell ， front & back cover ， high-performance temperature-resistant magnetic steel and imported high-speed bearingSpecifications:Model: 550KV(RPM/V): 3800KVPoles: 4PolesWatts: 1200WMax Voltage: <13V(2-3S Battery)Max Amps: 92AShaft diameter: 5mmConnector: 4.0mm gold plugRecommend model: Car，BoatPackage size: 9.5 * 8 * 6.3cm / 3.7 * 3.1 * 2.5inPackage weight: 260g / 9.1ozPackage list:1 * 550 3800KV BL Brushless Motor