Most of our stock grommets are made from Buna-N (Nitrile), however, we also manufacture custom grommets in a range of materials. For example, we use commercial grades of SBR, silicone, Neoprene, EPDM. Materials are available in commercial and specification grades, and requirements including NASM 3036 Composition A and B, Mil-Spec, ASTM, AMS, SAE, and others.