This is the Great Planes ElectriFly 6.0mm to 5/16-24 prop adapter with set screw and propeller nut.
Includes: Prop Adapter, 3.5x5mm Set Screw and 5/16 Propeller Nut
Requires: Installation onto the motor or gearbox shaft
Length: 1.7 (43.9mm) end to end, 1.17 (29.mm) complete shaft with 0.86 (21.9mm) threaded portion
Diameter: 5/16 (7.9mm) prop shaft, 0.23 (6mm) ID for motor shaft, 1.1 (28mm) largest part of hub (thrust washer portion) and 0.50 (13mm) smallest part of hub