Adam Hall 87530 Headphone Hook for 19" Racks
Can be removed and inserted from other end, which means can be placed on either left or right of rack. Be aware that it can’t have any rack screws under it, so will need to pass over a ‘blank’ space in the rack. I placed it over the bottom screw of a patch bay and it the bottom screw of a blanking plate below it. This meant removing the top screw of the blanking plate, but doesn’t matter as the other three screws held it in place.
Very handy and will order a few more, one for cable management within the rack and the other for my studio desk which has racks built in. Very handy!