One of Hammerhead's line of knives, including the Cranium, Ulna, Patella, and Ilium. These knives are named after the bone they are meant to be worn closest to. The Ulna, then, is designed to be worn in the arm, but can be worn anywhere on the body.
Hammerhead's proprietary processes create a very sharp, lightweight and durable knife. The blade is constructed from Stainless Steel, with a hardness of 55-56HRC. The knife is low-profile and designed to be worn close to the body, eliminating line traps and minimizing drag.
The Ulna is a minimalist blade, designed with the freediver in mind. Slim, strong and lightweight, the “Ulna” checks in at a mere 85 g and with a 7 cm blade length, is a serious tool.