RRT: rack rails (for custom millwork)RRT Series mounting rails for custom millwork are tapped to accept threaded 10 32 screws. Rails are made from sturdy 11 gauge steel and have a black powder epoxy finish with a printed scale showing rack unit increments to facilitate set up. HARDWARE NOT INCLUDED. Sold in Pairs. Model No. RU Mounting Hardware RRT 7 7 not included RRT 10 10 not included RRT 12 12 not included RRT 14 14 not included RRT 16 16 not included RRT 21 21 not included RRT 24 24