NAS1329 open end, flat head riv nuts are made of 5056-5 aluminum alloy with an anodized finish to MIL-A-8625 class 1 standard. Available in both keyed and keyless versions. This NAS1329 riv nut (EDMO# 1329A06120) is keyless, has a 6-32 thread size, and is 0.500 inch in length.