The Blackhawk Hook Back Holster is given a thorough look by Guns & Ammo's Eric Poole and James Tarr in this video segment and the pair find a functional holster with plenty of features.
Intended for use on Blackhawk's Diversion line of bags, the holster can also be used on anything that has a velcro attachment.
The holster can be adapted to fit just about any size handgun and, when paired with the Diversion pack, allows you to place your handgun in a variety of locations and at any orientation. Just press it in place and it stays put.
The system offers many levels of adjustment which allows for customization to fit your handguns and your preferred method of carrying them.