1. The lens collar is tailor-made for and compatible with Sigma 150-600mm f/5-6.3 DG OS HSM Contemporary Lens, cannot be compatible with Sigma 150-600mm f5-6.3 DG OS HSM Sports lens. | 2. The tripod mount ring's inner diameter is about 80.5mm, width is about 22.5mm, with 3M film inside, preventing lens from scratches; net weight is about 170g. | 3. The tripod collar bottom is added 75mm 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. | 4. The Lens support bottom reserved 1/4" and 3/8" screw holes and stainless-steel anti-slip screw for fixing lens to tripod directly. | 5. The tripod ring is made of Aviation Aluminum, CNC precisely machined, hollow-out weight reduction design, polished and surface anodized finish. The appearance and exquisite workmanship are much better than similar products made by mold.