The Arca-type-compatible QR-48Ns Quick Release Shoe from Markins is constructed from duralumin and has a hard-anodized, scratch-resistant surface. The clamp's jaws open with half to a full turn of the Quick Turn Knob mechanism. Inside the clamp is an integrated bubble level that helps to keep the ball head leveled when mounted via its 3/8"-16 socket. Also, a built-in safety-stop pin is located within the clamp to prevent a quick release plate from sliding out if the clamp is partially opened, and a scale is laser engraved on top of the clamp to help you repeat the position of a quick release plate in future uses.