Simpson Drag Boots are primarily intended for use with SFI 15 and SFI 20 Drag Suits and can be worn with other driving suits as an added safeguard. They're knee-high, made completely from Nomex (including the sole areas), and have side zippers for easy-on/easy-off use. Because you wear them over your shoes, they are available in six loose-fitting sizes ranging from small to extra-large. They're SFI 20-approved, come in black only, and feature the Simpson logo on the side.