Govt Issue Military Steel Toe Rubber Knee high boot. Toxicological Agents Protective Boots,M2A1(4). The M2A1 TAP Boots, Type I (4) are made of butyl rubber, have a safety toe with a yellow overlay compound applied to the outside, have a hobnail tread design on the sole and heel, and are knee-length. New. Heavy-duty boot, Size 7 only.