E-Flite UMX Propeller Adapter for BL180 Brushless Motor，Suitable for propeller with aperture of 4mm

Because the middle of the original propeller is thin, the washer is required

Installation

The middle of the GWS propeller is thicker, so it can only be fixed with the screw, and no washer is needed

Compare it with similar products of the WL XK430

WL's products will have two more bulges, which are very convenient for fixed  and are not easy to slip, of course, this universal type is very poor, and you can only use WL's own propeller