This is a set of Dubro Heavy-Duty Ball Links for use with 4-40 Threaded Rods. FEATURES: Black nylon link construction Brass swivel-ball construction Beveled brass swivel-ball stand-off Hex-Head machine mounting screw INCLUDES: Twelve Heavy-Duty ball links w/brass swivel-balls Twelve beveled brass swivel-ball stand-offs Twelve 4-40 x 5/8" hex-head mounting screws Twelve #4 lock nuts (metal construction w/nylon insert) REQUIRES: 3/32" allen wrench 1/4" open-end wrench or nutdriver SPECS: Ball Link Length: 27mm (1.063") Standoff Height: 3.2mm (0.125")