Whether you lost it, damaged it, or just want to keep a backup on hand, it's never a bad idea to have a replacement thru-axle on hand to save you from a future headache. The AX-MT700 Boost Thru-Axle from Shimano is available for the rear end of your 12 x 148mm boost bike with an overall length of 172mm and a thread pitch of M12 x 1. 5mm. It's a clean design that uses the much-lauded Shimano cam closure system for a secure and positive connection, and the adjustable tension adjustment allows you to easily position the lever so it doesn't interfere with the dropout or disc caliper. The lightweight aluminum construction and hollow axle allow this thru-axle to come in at a very svelte 76 grams.