Optional seismic bracket for 700 series racks. Can be certified in accordance to the Telcordia NEBS (network equipment building systems) GR-63-CORE standard. When the SBK-7-- brackets are properly installed, the 700 series successfully endured the rigorous real-world dynamic test - the racks are able to withstand up to a zone 4 earthquake which is comparable to Richter magnitude 8.0.