The tripod mount ring mount on the tripod, it helps you fix and balance your tele lens which is heavy or long lens hanging off the front of camera. RING: Advanced CNC processing,High quality Anodized aluminum alloy Color: Black The UNC (Unified National Coarse Thread) is 1/4″ and 3/8″ Suitable For: Sony FE 70-300mm f/4.5-5.6 G OSS(SEL70300G) Item Included: Lens Tripod Mount Ring x 1