Metric Nitrile O-Rings are one of the simplest, yet most engineered, precise and useful seal designs ever developed. These O-rings are made of high-strength Nitrile (Buna-N) rubber. Metric O-Rings are ideal for myriad applications such as DIY projects, plumbing services, and contracting work. Also included in Hillman assortment #56188 / label #98274.