Problem Solvers offers this kit for a specific need, as with all of their products. It is what the company was created for, and the well-made parts get their job done right. Their Booster thru-axle hub spacer kits are designed to give your non-Boost front and rear thru-axle hubs the boost they need to fit any Boost-compatible frame or fork. This kit adds 6mm of width (3mm each side) to a non-Boost 142mm rear hub, to meet the 148mm Boost width found on most mountain bikes. It includes a Center Lock rotor adaptor, allowing riders to use 6-bolt rotors on Shimano Center Lock compatible hubs