The Ball Link Sockets Snaps Securely Onto the Ball Part of the Ball Link. / / INCLUDES: Four Nylon Ball Sockets / / FEATURES: The nylon ball sockets will fit a threaded rod (2-56). / It will fit #GPMQ3840 or GPMQ3841 (Threaded ball link/single or bulk) / Easy to grip hex shaped shank / 4-20-94sk / ir/jl