Fit For EXC 300 EXCF 350 XCW 500 2024 SXF 450 SX 250 XC 300 XCF 2023-2024 Rear Axle Nut Rear Chain Adjuster Axle Block They hold the wheel precisely in place while you tighten the chain and stay in position when the axle is removed. The unique design means that only one 10mm wrench is needed to make your chain adjustments. A manual tensioner requires periodic adjustment. while automatic units self-regulate with engine oil pressure., Manufacturer: LKHJDBIY