This is a new technology Brushless motor, designed to work with Mid size Electric Helicopters like 500size
The motor comes Without Cooling Fins. If special High power application needed, please Purchase a Heat Sink for best performance

B40S used in helicopters like Eolo, Stinger/Viper, Quick 8 and others.
Some of cars and Airplanes using those motors as well.

Specifications:
Motor Type:B40-S
Speed: 3750 K v
Idle Current: 2
Resistance:0.0115
Length : 47 mm
Diameter: 28mm
Shaft Size 3.2 mm
Weight : 65 grm