Proforged 101-10122 Rear Upper Ball Joint 1,000,000 MILE WARRANTY. You can install our ball joints with confidence knowing that every part we sell is backed by our industry-leading 1,000,000 mile limited warranty. We can offer this because our parts are engineered, tested, re-tested, and subject to strict quality control procedures - our quality is second to none. CRAZY STRONG BALL JOINTS. Proforged ball joints are built using some of the toughest steel on the planet. Forged SAE4140 chromoly steel studs are enclosed in forged SAE1045 housings, heat treated for strength and durability, and every fit surface is CNC machined for precision fit and finish. Each unit is sealed with specially-designed CR-rubber boots for ultimate durability. BUILT FOR PROFESSIONALS. Theres a reason why the most well-respected performance suspension brands use Proforged ball joints - were fanatical about quality, performance, and durability. Professionals save time and money with our competitively-priced products that outlast inferior brands. Do the job with confidence - replace your worn components with the leader in performance ball joints: Proforged. WHAT IS A BALL JOINT? A ball joint is an enclosed spherical bearing that connects the control arm to the steering knuckle or spindle - it is a ball-and-socket design, just like your hip, and it needs to be replaced as it wears out. A worn ball joint causes poor handling and makes it difficult or impossible to achieve an alignment, which leads to rapid tire wear. Replacing your worn ball joints gives a noticeable improvement in steering feel, handling, and safety. BUY WITH CONFIDENCE. Theres a reason that the most well-respected performance suspension manufacturers buy from Proforged: were the only brand of chassis parts that offers race-day performance at a price within your budget - and backs it up with a 1,000,000 mile limited warranty. Buy today and get your car, truck, or racecar back on the road and stronger than ever.