UL Listed in the US and Canada Tool-Free Quick-Mount system allows for easy, one-person mounting of the center section to the backpan on the jobsite Available in 15 , 20 , 24" and 30 useable depths Welded construction provides up to a 300 lb. weight capacity, depending on model Abundant built-in cable lacing points in interior , , 1 , 1 , 2 and 3 electrical knockouts and 5/8 UHF/VHF antenna knockouts on top & bottom, easily removable for cable pass-through 12 x 12 laser knockout opening in the backpan for electrical pull-box Abundant Velcro and internal cable tie points Finished in a durable black textured powder coat Standard adjustable front 11-gauge 10-32 threaded rackrail with marked rackspace increments to speed equipment mounting Center section hinges for left or right opening accessories 2" knockouts, 4" knockouts for Wiremold 4000 Series raceways, and knockouts for UCP series universal connector panels on side Grounding/bonding stud in top and bottom of center section and backpan facilitates proper grounding and bonding of electronic equipment, as per NEBS and NEC standards Front Mounted Minimum-Clearance Latch saves valuable wall space by allowing wall racks to be placed side-by-side, in a corner, or wherever side clearance is an issue. Seismic certified to the following codes and standards: 2007 & 2010 CBC; 2006, 2009 & 2012 IBC; ASCE 7-05 (2005 Edition) & ASCE 7-10 (2010 Edition) and the 2006 & 2009 editions of NFPA 5000 for use in areas of high seismicity Zone 4 or Seismic Design Category (SDC) "D". These are designed for Mission Critical and/or High-Importance Installations in locations with the highest level of seismicity and top floor or rooftop installations including those within UBC and CBC Essential facilities or IBC, ASCE 7, and NFPA 5000 Seismic Use Group III facilities. For all codes, the Importance factor (Ip) is 1.5. Seismic Certified load capacity of 140 lbs. when used with DWRSR-ZL Latch.