Suitable for EF 70-200mm f/4L USM, for EF 70-200mm f/4L IS USM, for EF 300mm f/4L USM, for EF 400mm f/5.6L USM. It helps you fix and balance your tele lens which is heavy or long hanging off the front of camera. Aluminum alloy construction, anti-rust and lightweight, durable to use. Nice accessory for photography lovers, bringing you better experiences. Easy to install with a fixing screw stud and convenient to use.