uxcell 50pcs 13mm Outside Dia 1mm Thick Flexible Nitrile Rubber O Ring Washer Product Name : Nitrile Rubber O Ring;Material : Nitrile Rubber (NBR) Inside Diameter : 11mm/0.43";Outside Diameter : 13mm/0.51" Thickness : 1mm/0.04";Color : Black Weight : 3g Package Content : 50 x Nitrile Rubber O Rings