This super clamp is made of strong, rust-proof stainless steel + black anodized aluminum alloy for great durability. Can mount virtually anywhere you need like cameras, lights, umbrellas, hooks, shelves, glass plates, crossbars, and even other super clamps. The 1/4" and 3/8" on the back of the clamp. You can mount other accessories via the 1/4'' or 3/8" thread, such as SMALLRIG Ball Head Arm 2070/2157/761. The jaw opens up to about 2.3" (58mm), and minimum 15mm. You can clip it on anything less than 40mm thick and more than 15mm, it works better. Anti-slip and Protection: The rubber pads on the metal clamp make it not easy to slide down and could protect your item from scratches.