This is a Swivel Ball Link set by Dubro. This set is designed for use with 4-40 threaded rods. Black plastic construction. Brass swivel ball. Full hardware package. Two Ball links with inserted brass swivels. Two 2.2x13mm hex head screws. Two 5x3x2.5mm brass spacers Two Silver 2.2 hex nuts. 4-40 rods Assembly onto kit. Length: 25.2mm (.994") Inside diameter of swivel: 2.8mm (.112") The screws used to mount the link are 2-56 size. pjm 4/10/02 ir/kh &