The Petzl 12mm Single Unit Anchor Bolt available at OmniProGear is made of standard steel and designed for interior use or in non-permanent installations. Petzl hangers have attachment holes that are large enough so make the process of clipping carabiners easier, and you can install two carabiners in the same anchor, even if they have a greater than average thickness. The texturing on the back side of the hanger that comes in contact with the concrete or rock will preclude the hanger from turning during installation of the anchor. Standard steel, designed for interior uses or non-permanent installations. Easy clipping Featuring a large attachment hole, Petzl hangers facilitate clipping carabiners and allow two carabiners to be installed, even thick ones, in the same anchor. Preventing connector wear Petzl hangers are characterized by high thickness, and rounded edges on the attachment holes. This construction minimizes wear on connectors, regardless of their material composition. Hanger anti-rotation system Petzl hangers are textured on the back side that is in contact with the structure (concrete, rock...). This helps prevent the hanger turning when the anchor is being installed, or when it is heavily side-loaded in use., Sporting Goods, Outdoor Recreation, Climbing, Climbing Protection Devices