Kalevel 20pcs Airplane Propeller 3.17mm Prop Adapter 3.17mm Prop Saver Prop Adapter 3.17mm Rc Plane Prop Saver 3.17mm with Screws Rubber O Rings Kit for Brushless Motor Shaft Material : Rubber (O Ring), Aluminum (Prop Saver) Can be used on any brushless motor with a 3.7mm shaft Package Content : 4* Prop Saver + 8* Rubber O-Rings + 8* Screw =20pcs in total Aluminum construction Silver in color Helps to save the prop when landed or crashed 100% brand new and high quality Kalevel 20pcs Airplane Propeller propeller adapter Prop Saver with Screws Rubber o rings kit for Brushless Motor Shaft