The Sigma TS-111 Tripod Socket is a single-locking knob collar that offers more balanced support  For 100-400mm f/5-6.3 DG DN OS Contemporary Lens for Sony E & Leica L lens when used atop a tripod or monopod. Once the collar is on, it enables the lens and camera to turn on axis in a vertical or horizontal position. In addition, the dovetail foot on the tripod socket is compatible with most Arca-type clamps.