The material is silicon
NSN 6220-01-614-0563
NSN 5996-01-349-7059
NSN 5910-00-603-7043
NSN 5930-00-993-8365
NSN 5960-00-952-1868
NSN 5930-01-212-7785
NSN 6130-00-951-2942
NSN 7035-01-391-7470
NSN 5999-00-198-3959
NSN 5895-01-096-4268
NSN 6645-01-460-4339
NSN 5925-00-420-8561