This aluminum tripod collar mount ring is specially designed for Canon EF 70-300mm f or 4-5.6L IS USM, balancing the lens and the camera, making it more convenient for you to adjust the lens after fixing on tripod. Ring inner diameter: 81.5mm, Ring width: 18mm, Ring thickness: 4.5 - 8mm, Color: White. Just spin the knob and pull it out, you can release the ring.   Features: Designed for Canon EF 70-300mm f or 4-5.6L IS USM, balance long lens and camera, protect it away from unexpected dropping.  Make it convenient for you to adjust the lens after fixing on tripod.  Ring inner diameter: 81.5mm, Ring width: 18mm, Ring thickness: 4.5 - 8mm, Color: White.  Made of strong and durable aluminum, fine workmanship ensure perfect conformity in color and surface qualities.  Spin the knob, pull it out to unlock it, tightened locking system.  Soft inner ease the pressure on your valuable lens.  With a 1 or 4" female screw on the bottom.   Specifications: Material: Aluminum   Compatibility: For Canon EF 70-300mm f or 4-5.6L IS USM   Ring Inner Diameter: 81.5mm   Ring Width: 18mm   Ring Thickness: 4.5 - 8mm   Item Weight: 161g or 5.7oz   Package Size: 14.2 x 9 x 8cm or 5.6 x 3.5 x 3.1in   Package Weight: 230.5g or 8.1oz    Package List: 1 x Tripod Collar Mount Ring Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-YJL official store