Kū is the Hawaiian god of war, among other things. One of the four great gods, the other three are Kanaloa, Kāne, and Lono.
This embroidered patch has Velcro hook backing for attachment to any Velcro loop backing on hats, helmet, plate carriers, vests, backpacks and bags, and comes with a matching Velcro loop piece you can sew onto any fabric not already equipped.