Specification: Product: Bike Cassette Spacer Thickness: 1.0mm / 1.5mm / 2.0mm Inner diameter: 33mm / 1.30inch (with teeth); 35mm / 1.38inch (without teeth) outer diameter: 39mm / 1.54inch Material: Aluminum Alloy Color: Black Package includes: 3 x Bike Cassette Spacers (one for each size) Suitable for adjusting the bottom bracket, flywheel or wheel hub of mountain bikes and road bikes. Note: 1. Due to the light and display, the actual color will be slightly different from the picture. 2. The dimension data are all measured manually, and there may be some errors.