1. This lens collar is tailor-made for Sigma 135mm f/1.8 DG HSM Art Lens (for Canon EF Mount, Nikon F Mount, Sony E Mount), can't be used for other lens; laser scanning technology is used to accurately obtain the lens parameters, and then the shape of the inner diameter of the lens support is accurately carved based on the data. | 2. The tripod collar is positioned by the switch and bayonet. Cannot be rotated. All corners are rounded. The inside of the tripod ring is covered with 3M plastic film to prevent lens wear. Inner diameter is about 83mm, width is about 25mm; bottom is added quick release plate feature, plate length is about 70mm, with 1/4 and 3/8 screw holes and stainless steel anti-slip screw; the net weight is about 175g. | 3. The tripod mount ring is made of high-density Aviation Aluminum; precisely machined by world-class high-end CNC turning center and hollowed-out carved by diamond combined cutter heads; adopting vibration polishing technology, which improves grinding precision by 20% than manual; multiple anodized, which improves the fineness and uniformity of the color of the metal surface by 10%; the appearance and exquisite workmanship is much better than similar products made by mold. | 4. This lens support bottom is AS standard quick release plate, compatible with RRS / ARCA-SWISS / PMG / WIMBERLEY / MARKINS / PHOTOCLAM / SUNWAYFOTO / BENRO / SIRUI / MARSACE / ISHOOT tripod 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 clamp. | 5. Package Includes: 1 x iShoot Tripod Mount Ring IS-SM135ART (The other items in the photos not listed here are for illustrating only, not included.)