This Quiklok RS656 Vertical Add-on extends your rack setup by 10 spaces. Youll be able to securely hold your gear with it up to a depth of 18 inches. It can also be stacked up to 30 rack spaces high with other units giving you plenty of space for everything you need. The RS656 is constructed with super-solid heavy guage steel and is also arc welded. Youll know because of this that this unit can go the distance. Plus rear access convient handrails and a 150lb capacity make this the ideal choice for extending your rack.