The material is silicon
NSN 6130-01-512-8510
NSN 5855-01-154-3871
NSN 6645-01-042-4220
NSN 5950-01-183-9480
NSN 5855-00-494-9581
NSN 6135-01-334-3935
NSN 6685-00-753-0668
NSN 6610-01-286-9597
NSN 5990-00-081-3937
NSN 5895-00-078-9281
NSN 5975-01-187-7744
NSN 5910-01-608-5641