The ProStaff Suspender Harness Binocular Strap from Nikon distributes your binoculars' weight across your back and shoulders and keeps them close to your body to prevent swinging around. It is highly recommended when using your binoculars during activities where you'll be moving around quite a bit. An added benefit to a suspender harness strap is that you'll be able to hold your binoculars steadier thanks to the elasticity, which maintains a bit more tension, lending significant support. It attaches to any binoculars, though those with objective lens diameters exceeding 50mm are not recommended.