This is the Great Planes ElectriFly 20mm Ammo gear drive. The motor attaches to the mount and the prop attaches to the gear drive.
Requires: Attaching to the motor shaft
Length: 1.84" (46.7mm)
Width: 1.66" (41mm)
Weight: 0.42oz (12g)
Motor output shaft dimension: 2mm
Prop adapter shaft dimension: 3mm
Gear ratios included: 5.3:1 and 6.4:1, 5.3:1 with 12T pinion and 64T spur, 6.4:1 with 10T pinion and 64T spur