uxcell 50x NBR 20mm x 1mm(ODH) Hole Sealing O Rings Gaskets Washers for Automobile Product Name : O Ring;Material : Nitrile Rubber(NBR) Quantity : 50Pcs;External Diameter : 20mm / 0.787" Inner Diameter : 18mm / 0.708";Thickness : 1mm / 0.039" Color : Black;Weight : 4g Package Content : 50 x NBR O Ring