The Gator Cases GRR-4L Roller Rack Case (Black) is a high-density military grade lightweight polyethylene case with 4U rack space and 18.75" rackable depth. The case has front and rear rack rails and threaded field replaceable 7.0mm zinc plated steel rack rails. It also has locking front and rear lids and heavy-duty twist latches. The case can be transported by comfortable recessed side handles, a rugged pull-out handle and roller blade style recessed wheels.