Used for fastening a harness and backplate securely to a diver's body, one end of the strap is threaded onto the backplate and the other end with a loop is placed on the waist belt webbing. The crotch straps keep the harness in place during water entry. By using a crotch strap, divers can prevent their gear slipping upwards on the body in the water, reducing the likelihood of the tank touching the back of the head during a dive. Crotch Straps include a stainless steel scooter ring for use with diver propulsion vehicles (DPV's). The ring is also a convenient place to temporarily clip off an item to free your hands, such as a lobster snare or camera.

The most common size crotch strap is now the (1.5 in / 3.8 cm) version as it offers an excellent compromise for most divers. A (2 in / 5.1 cm) strap is ideal for technical doubles and extended scooter rides with exploration, while the (1.5 in / 3.8 cm) version is more suitable for Open Water single tank dives and recreational diving. The (1 in / 2.5 cm) and the (1.5 in / 3.8 cm) crotch straps include a (2 in / 5.1 cm) scooter ring, a quick disconnect Fastex clip for easy doff and don as needed, and a Triglide belt slide for installation. Compatible with all OMS products, backplates, and harnesses.