NOTE: This part is designed to fit models with a black painted, tubular steel upper shaft that is about 9/16-inches (approx 14mm) in diameter. Earlier models, built before mid-2015, use a chrome plated solid steel upper shaft that is approximately 5/16-inches (8mm) in diameter. This ball will NOT work properly on old models with the thinner shaft. Update: As of late 2019, replacement balls for the old chrome shaft stand are no longer available.