Precision Design Tripod Mount Ring Collar CA(W) for Canon EF 70-200mm f/4L USM & Canon EF 70-200mm f/4L IS USM Zoom Lens Tripod Mount Ring Collar CA(W) for Canon EF 70-200mm f/4L &amp; f/4L IS USM Achieve better balancing on a tripod Makes rotating the camera much easier and faster