***These speaker spike/insulation pads are made of solid aluminum with a machine fine finish. They have a diameter of 20 mm and a thickness of 7 mm. Central register hole to ensure spikes are locked correctly. Prevents damage to wood/laminate floors. Excellent for speaker cabinets to ensure even grounding. Mass stability for excellent bass performance. Can be used in conjunction with adjustable spikes to stabilize/isolate turntables. For delicate surfaces, please use our self-adhesive felt pads in our Amazon store. 15mm felt pads for 20mm speaker spike pads, 12mm felt pads for 16mm speaker spike pads. 100% SATISFACTION GUARANTEE - If you are not 100% satisfied with your purchase, please just contact and we will do our absolute best to get things right. We always try to ship on the same business day where possible if orders are received on time