5100 Kv (rpm/volt), 50 grams (1-3/4 oz.) weight, 130-290 watts. Total length of motor and adapter (face of mount to rear of motor shaft) is 54mm (2-5/16"). Adapter diameter is 21mm (13/16"), length without shaft is 22mm (7/8"), motor shaft is 3mm.
The motor has the 21mm adapter pre-installed and ready to assemble into the ETH550 56mm fan (available separately). The cooling is exceptional; the motor is completely exposed in the exhaust air of the fan. Motor will spin the fan at approximately 46,000 RPM on a 3-cell Lithium battery and draw less than 14 amps. With a 4-cell battery the RPM is over 60,000. Never static test this motor for more than 30 seconds.