XINJIHUI NITRILE RUBBER WASHERS O RINGS KIT 15 SIZES 200 PIECES. – Material: Nitrile Rubber(NBR). 【 Easy to Use 】 Soft and flexible o ring, simply snap on, easy to install. Used for sealing gasoline, diesel oil, lubricating oil, water, air, gas, and great for most plumbing, automotive, and general repair needs.