This tripod mount ring is compatible with selected Canon telephoto lenses, giving photographers an alternative point at which to attach a tripod. When shooting with long lenses, excessive strain can be put on a cameras lens mount by long or heavy lenses, however this tripod mount ring provides a more balanced set up. Compatible with EF 400mm f/5.6L USM, EF 70-200mm f/4L USM, EF 70-200mm f/4L IS USM and EF 70-200mm F/4L IS II USM lenses. Benefits Reduces stress on your cameras lens mount when using longer lenses Helps with handling when shooting with a tripod Allows fast repositioning between horizontal and vertical shooting Compatible with EF 400mm f/5.6L USM, EF 70-200mm f/4L USM, EF 70-200mm f/4L IS USM and EF 70-200mm F/4L IS II USM lenses What\'s in the box Tripod Mount Ring A II (WII) - White Compatibility EF 70200mm f/4L IS II USM