TOOGOO(R) 3.17mm Hole Dia RC Propeller Prop Saver Adapter w Black Rubber O Ring 20mm x 3mm Product Name : Prop Saver w O Ring;Material : Rubber (O Ring), Aluminum (Prop Saver) Color : Black, Silver Tone;O Ring Size : Outside Diameter: 20 mm / 0.787",Inside Diameter: 14 mm / 0.55",Thickness: 3 mm / 0.118" Prop Saver Size : 10 x 8 mm / 0.4" x 0.3" (D*T);Hole Diameter : 3.17 mm / 0.125" Weight : 3g Package Content : 1 x Prop Saver,2 x O Ring