TR-1 tripod mount ring replaces Canon Tripod Mount Ring A-2 is the tripod collar for the EF 70-200mm f/4L (IS and non-IS versions) lens. By adding a tripod collar to your lens you can achieve better balancing on a tripod. In addition, rotating the camera will now be much easier and faster. Made by metal with high quality. Suitable for Canon EF 70-200mm f/4L USM, EF 300mm f/4L USM, & EF 400mm f/5.6L USM SLR Lenses.