Secure cameras/optics via ¼ 20 photo screw to this 2" D-ring and directly to your sling-pack strap or sternum strap.This patent-pending design turns our pack straps into secure, comfort padded instant camera slings. You can even add a quick release clamp like Arca-Swiss type or Manfroto to go from strap, to tripod, to gimbal and back into your pack. The length can be adjusted from super tight for carry, to long for reach. Comes with a replaceable rubber traction pad to minimize camera spin that can be stored under the screw head (screws sold separately since you'll want to find one that suits your application best). The threaded hole secures the screw from falling out easily.