Fully welded construction, solid sides 2,500 lb. weight capacity UL Listed in the US and Canada Seismic certified (UBC 1997 & CBC 1998 Zone 4; IBC 2000, IBC 2003, ASCE 7 - 02, NFPA 5000 Seismic Use Group III) for protecting 650 lbs. of essential equipment when used in conjunction with our ERK-Z4 brackets 1/2", 3/4", 1" and 1-1/2" electrical knockouts found on NEW! 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