The Spicer SPL170 Joint Strap Kit keeps you Ready for the Road Aheadâ„¢, locking your u-joints to the driveshaft, pinion, and axle yokes. Bumpy roads or rough terrain can cause vibrations, potentially causing harm to your vehicle's u-joints and may cause them to separate and damage other parts of your semi truck. Properly secured u-joints are paramount to safety and long-standing performance, while preserving your driveshaft.