SKB 1SKB-R4U Standard Roto Rack is roto-molded of Polyethylene (LLDPE) for extra strength and durability. The exterior features SKB's recognizable bar design that signifies the rack unit size on the front and rear lids. Molded bars on top and bottom also provide interlocking capabilities allowing you to easily and securely stack them with SKB's Shallow Racks and Roto Rolling Racks, making transport even more convenient and secure. Lids include rubber gasket seals to keep water out. Other standard features include front and rear steel threaded rails and rack screws (10-32 thread), recessed steel Mil-Spec twist latches, flush carry handles, and non-slip rubber feet. All Standard Roto Racks are 17.6" deep from front rail to rear rail.