This is plastic Swivel Ball Link with Adjustable tension by Dubro. This is used in conjuntion with 4-40 threaded rods.
Features : Adjustable swivel tension using screw adjustment. Black plastic construction. Burnished brass swivel ball for smooth operation. Full hardware included.
Includes : Two linkages. Two brass swivel balls. Two 2 x 6.5mm slotted head tension adjustment screws. Two 2.6 x 15.5mm hex drive screws. Two 6.5 x 3.5 x 3mm tapered spacers. Two 2mm hex nuts.
Length : 23.5mm (.925 in.)
Inside Diameter of Brass Swivel : 3.3mm (.132 in,)