Description: Aluminum thumb knob with stainless bolt nut screw for HE & HD & HD HERO3 mount adapter. Made of high quality high-strength, high rigidity & precision craftsmanship CNC machining aluminium alloy, more wearable and durable, provides long life. You can easily tighten the screws between the rack and the camera to attach the camera to a tripod or bicycle. A small rubber ring is good for preventing abrasion, yet it is not essential for everyone so put them away when you don't need it. Three pieces, two sizes of screw, can fully meet your installation needs, multiple colors to diversify your choices. Specification: Material: Aluminum Alloy Long Screw Size: 5.5x2cm/2.17x0.79inch Short Screw Size: 4x2cm/1.57x0.79inch Package Includes: 1 Piece Long Screw 2 Pieces Short Screws 3 Pieces Screw Caps 3 Pieces Washers Note: Color might be slightly different due to the color calibration of each individual monitor. Please allow slightly measuring deviation due to manual measurement.