The tripod mount ring mount on the tripod, it helps you fix and balance your lens which is heavy or long lens hanging off the front of camera. It features Arca-compatible dovetail plate which allow you attach your lens to Ball Head, Clamp or Panorama Head of Arca- standard. Reserved multiple 1/4"-20 & 3/8"-16 thread screw holes at the bottom for attach lens to tripod directly. Made of aviation aluminum alloy and CNC machining, treatment, right weight and strong building. Specifications: Made by metal with very high quality The UNC (Unified National Coarse Thread) : 1/4" & 3/8" Compatibility: Arca- Standard Ring inside diameter: 85mm/3.34inch Baseplate Length: 70mm/2.75inch Baseplate Width: 40mm/1.57inch Color: black Net Weight: 231g/8.15oz Compatible with: For AF 135mm F1.8 LAB FE Full Frame Lens for E-mount For AF 135mm F1.8 LAB Z Full Frame Lens for Z-mount Material: Aluminum Alloy Package Contents: 1 x Lens Tripod Mount Ring Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.