Tool-Free Quick-Mount™ system allows for easy, one-person mounting of the center section to the backpan on the job site. The EWR-12-22 has a racking height of 21" (12 space). Center section hinges for left or right opening. 1/2", 3/4", 1", & 1-1/2" electrical knockouts and 5/8" UHF/VHF antenna knockouts on top & bottom, easily removable for cable pass-through. 10-1/2" x 10-1/2" laser knockout opening in the backpan for electrical pull-box. Abundant lacing points throughout the interior facilitate cable management. This is the perfect rack for your musicBox components.