Heavy-Duty Double Cover Case has two removable lids. Each area inside can be separated to have two specific halves or the case can be fully open from the front to the back. This style case is also used for Rack case and rack rails can be installed for your rack-mountable gear. Cases can be madewith 1/4, 3/8, and 1/2 inch walls. Heavy-Duty shipping cases are designed to meet ATA ( Air Transport Association ) standards.