WHEELS MANUFACTURING ALLOY CHAINRING SPACER BAG/20Chainring spacers help you adjust the chainline of your inner and middle chainrings. If your chainline isn't properly lined up with your cassette on the rear, it can cause shifting and performance issues. The Wheels Manufacturing Alloy Chainring Spacer Bag comes with a pack of 20 spacers so you can adjust the chainline on the inner and middle rings. These spacers come in either an 8mm or 10mm inner diameter, depending on option selected. Features Bag of 20 in case you need multiple spacers8mm inner diameter for 1. 2, 3. 5 and 2mm options10mm inner diameter for 2. 2, 4, and 5mm options | Wheels Manufacturing | Alloy Chainring Spacer Bag/20 2. 0Mm