1.1. The tripod mount ring is tailor-made for Canon RF 70-200mm f/2.8L IS USM Lens, can't be used for other lenses?the inner diameter is about 81.5 mm, the width is about 13.5mm, net weight is about 165g; 2.2. The lens collar adopts original E(III) standard design, split structure, the inner wall is grooved, and the 3M plastic film is attached to reduce wear; the knob has the same function as the original factory, and the knob is screwed to the end to unlock; 3.3. The tripod collar bottom is added 70mm long Arca fit quick release plate feature, can be used with 39mm Arca-swiss fit tripod ball head, panoramic head and clamp directly; more practical than lens collars without QR-Plate. The Lens support bottom reserved 1/4' and 3/8' screw holes and stainless-steel anti-slip screw for fixing lens to tripod directly; 4.4. This lens support bottom's dovetail groove is 39mm Arca-Swiss standard, compatible with RRS / ARCA-SWISS / PMG / WIMBERLEY / MARKINS / PHOTOCLAM / SUNWAYFOTO / BENRO / SIRUI / MARSACE / ball head of Arca 39mm fit, suitable for IS-JZ30 / IS-JZ50 / IS-JZ64 / IS-QJ58 / IS-QJ64-FD / IS-JZ60BK / IS-JZ70MFT / IS-JZ80BK;