This is a unique bearing in that the inside race is extended 1mm on both sides. So the bearing is 8mm ID, 22mm OD, and has an outer race thickness of 7mm and an inner race thickness of 9mm. This cannot be used in normal wheelchair caster wheels and is not considered a standard 608 bearing. IF YOU HAVE QUESTIONS, PEASE CONTACT US. Manufacturers suggest you service your wheelchair at least once a year. Your wheelchair, if not properly maintained will cause long-term damage to your body. Putting new bearings in your wheelchair and properly maintaining them is something you can do at home and will greatly reduce wear and tear on your body and allow you to go faster and roll farther. We have developed a set of tools, found great bearings, and show you how to do it. More zoom less squeak. We use high-quality bearings made for the professional cycling industry. The bearings are designed to handle harsh environments and keep on working. Each of our Bearing Kits comes with 4x high-quality bearings, 2x cotton swabs for cleaning and remove any old grease, 2x acetone wipes to clean hubs before re-greasing them, 1x high-quality grease packet to add an anti-seize bearer between the bearing and the hub and a step by step instruction booklet to make sure you are on track. Features: Double lipped rubber seals keep water and grime out and grease in longer ABEC 1 High-quality bearings make for a smoother ride High-quality synthetic grease adds to a longer life, rust prevention, and smoother ride We have these bearings made for us specifically for wheelchairs. Problems this product solves: Problem 1: Most wheelchair bearings not designed for performance usage
 Problem 2: Most wheelchair bearings not designed to high smoothness over the longest period of time
 Problem 3: Most wheelchair bearings are not designed to be serviced
 Problem 4: Most wheelchair bearings do not use the highest grade materials Used on the following wheelchair products with 8mm axles: Used in some Karma / Karmen Health Care Wheelchairs Drive Medical STDS1011 (Not STDS1011HD) Fold & Go Wheelchairs What you need before you get started: Paper towel or clean rag Hammer Swear jar 2x adjustable wrenches 8mm blind bearing puller tool Bearing installation tool/ bearing press Pin punch Bearings Clean work surface Warnings: Improper removal or installation of bearings can permanently damage casters, rear wheel hubs or caster stems. Please use caution when using brute force. Make sure you know the size and types of bearings on your wheelchair and buy the right sizes. If you have questions or if we can help please contact us.