This is a 5/8" Baby Pin System, from Inovativ, for use with any Inovativ cart. It consists of a 30"-long 5/8" baby pin rod and two clamps. Clamp the 30" baby pin rod to any of the 4 posts of an Inovativ cart and then attach anything compatible on top, such as a laptop tray. Featuring two 3/4" holes, the system allows you to run up to two baby pin rods with full height and swing adjustability.