Check the listing for details. ProX XS-RSS1U Rack Rail Hardware Kit for ProX DJ Controller Flight Case. Condition: New with tags. Listed at 12.99 USD. Add Rack Rails to Your ProX DJ Controller Case The ProX XS-RSS1U fits any ProX DJ Controller case with a 19-inch minimum opening and at least 1-3/4-inch space beneath the controller. Sweetwater DJs find the XS-RSS1U perfect for adding a front- or rear-rackmounted power strip, wireless mic system, or other such 1RU gear underneath the sliding laptop tray of most ProX DJ controller cases.ProX: quality, without compromise Founded in 1984 by a group of music and entertainment industry veterans, ProX leverages extensive firsthand experience to provide professionals with the highest-grade gear possible.