1. The tripod mount ring is tailor-made for Canon EF-EOS R adapter ring, CAN only be used for EF-EOS R basic models, not for models with filters or focusing rings; relying on the switch and bayonet positioning, cannot rotate in the tripod ring; when shooting vertically, the EF-EOS R adapter ring needs to be taken out and reinstalled. | 2. The tripod collar using laser scanning technology to accurately obtain lens parameters, and then accurately carve out the shape of the inner diameter of the tripod ring according to the data. The edges and corners are polished, the inner wall is affixed with 3M plastic film, preventing the lens from scratches; the shortest inner diameter of the lens holder is about 73mm, the width of this contact surface is about 18mm; net weight is about 145g. | 3. The tripod collar bottom is added 55mm 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 screws for fixing lens to tripod directly. | 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 / ISHOOT ball head of Arca 39mm fit, suitable for iShoot IS-JZ30 / IS-JZ50 / IS-JZ64 / IS-QJ58 / IS-QJ64-FD / IS-JZ60BK / IS-JZ70MFT / IS-JZ80BK. | 5. The tripod ring is made of high-density Aviation Aluminum, precisely machined by world-class high-end CNC precisely machined, hollowed-out work processed by Multi-Diamond Cutter finely, lightweight and solid. Polished and surface anodized finish. The appearance and exquisite workmanship are much better than similar products made by mold.