5-inch speaker spacer: Good for DIY car audio modification projects. Can be used in cars, trucks, RVs, etc. Thickness: 12mm / 0.47"; Inner Diameter: 120mm / 4.72"; Outer Diameter: 160mm / 6.3"; Mounting Hole Diameter: 5mm / 0.2", 3mm / 0.12" Fits most speakers on the market. Solves the problem of installation depth. Durable material, it is made of plastic which is useful and long-lasting. Package includes: 4 x Universal Car Speaker Spacers