1、Made of high-quality aluminium alloy, fadeless and not easy to oxidize. 2、Amplifier feet to help absorb shock, to protect your amplifier. 3、Rubber ring is detachable, very convenient and easy to use. 4、Durable for a long-time use. 5、To raise the height of amplifier to help create a real stereo surrounding sound. Features: Made of high-quality aluminium alloy, fadeless and not easy to oxidize. To raise the height of amplifier to help create a real stereo surrounding sound. Amplifier feet to help absorb shock, to protect your amplifier. Rubber ring is detachable, very convenient and easy to use. Durable for a long-time use. Specification: Type: Amplifier Feet Material: Aluminum Alloy Diameter: 20mm Height: 8mm Screw hole diameter: 3.5mm Surface treatment: Anodizing sand blasting Rubber ring: Detachable Weight: Approx. 22g Package list: 4 * Amplifier Feet Note: Please allow slight error due to manual measurement. Thanks for your kind understanding. Installation Method: The  amplifier feet can be installed from the inside of the chassis, or it can be installed from the outside of the chassis with self-tapping screws (suitable for wooden materials, self-tapping screws need to be self-matching, which means it's NOT included), or for 3M double-sided adhesive (self-matching, also NOT included)