20" Outside Depth (18.5" Useable). ERK 19" Stand-Alone Enclosures. Fully welded construction, solid sides, 2,500 lb. weight capacity, UL Listed in the US and Canada, 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 600 lbs. when used with ERK-Z4 seismic floor anchor brackets, 1/2", 3/4", 1" and 1-1/2" electrical knockouts found on removable split rear plates, top knockout plate additionally includes UHF/VHF antenna knockouts, 16-gauge steel tops, bottoms, & sides, Laser-cut 1/8" thick internal steel braces for strength, 1 pair fully-adjustable front rackrail, Large cable entry in bottom, Grounding and bonding stud installed in base, Configurable top (44, 40, 35 sp.), solid top with fan KO s (27, 21, 18 sp.), Laser KO s in side panels for cable pass-through (44, 40, 35 sp. only), Finished in a durable black textured powder coat.