Alignment marks on the collar allow for quickly changing the orientation from portrait to landscape. You can use either a 3/8"-16 or a 1/4"-20 tripod mount using the included bushing adapter.
Improves Camera/Lens Balance The collar allows you to attach the lens to your tripod or monopod, instead of your camera, thus reducing stress on the camera's lens mount.
Rotation Having the camera secured with a ring around the lens makes it possible to rotate the lens between landscape and portrait modes without removing the camera from the tripod. The friction thumbscrews can then be tightened to secure the camera in the desired position. When not needed, the foot can be rotated to an out of the way position.
Safety Lock The thumbscrew loosens to allow collar rotation, but must be pulled out from the collar in order to remove it from the lens. This prevents accidental drops.