The Lens Flipper for Canon EF/EFs and Nikon Mount Lenses is a two-sided locking mount provides a fast and effective way for carrying and switching lenses in the field With a two-sided lens locking mount and sturdy shoulder strap.Quickly attach your working lens to the Locking mount, remove your alternate lens and attach it to your camera Sturdy lugs and 1"-wide adjustable length shoulder strap secure even heavy lenses and keep them conveniently at your side.