Installing a ball joint on a lower control arm typically requires the effort of two peopleWith this tool and our 7420 or 7421 pry bar or any 7/8" diameter pry bar it's a one-person jobLifetime limited warrantyInstalling a ball joint on a lower control arm typically requires the effort of two people. However with this tool and our No. 7420 or 7421 pry bar - or any 7/8" diameter pry bar - it's a one-person job.