SKB's 3RS Series Static Shock Rack Transport cases are available in 8 sizes: 3U, 4U, 5U, 6U, 7U, 9U, 11U and 14U. These Shock Racks are lightweight, shockproof, watertight, dustproof, heat and chemical resistant, and perfect for protecting and transporting your sensitive electronic equipment. The inner rack chassis is built of high strength (but lightweight) aluminum alloy extrusions with 11 gauge hot rolled carbon steel rack rails to meet EIA-310 standards. Shock and vibration mitigation is accomplished with eight (8) elastomeric isolators rated for a payload range of 40 lbs to 150 lbs in a standard configuration (optional extended payload range of 160 lbs to 300 lbs can be accommodated as a special order option). The interior frame and shocks provide adequate sway for ambient air circulation and heat dissipation. 3RS Series cases are molded of LMDP Linear Medium Density Polyethylene plastic that meets or exceeds MIL-STD 810G standards. Measuring 20" deep from rail to rail with a standard 19" rack width per ANSI/EIA-310-C specification, 3RS Shock Racks also feature square-hole rack rails to accommodate either 10-32 US standard or 6mm International standard cage nuts which are supplied with the cases. The rugged roto-molded shell ensures industry leading strength and impact resistance. The standard commercial off the shelf (COTS) case comes with 2" deep front and rear lids to accommodate rack gear that is longer than 20". Molded-in stacking ribs and lugs are designed to stack with all SKB 3RR and 3RS cases, as well as competitive manufacturer cases, and feature black powder coated stainless steel hardware that is recessed for protection and 4 comfort grip spring loaded lift handles which allow for easy movement. An automatic pressure relief valve is another standard feature along with gasket sealed lids that include convenient lid hangers to store your lids when your equipment is in operation. Coupling straps are included for securing the racks together when stacked. Available in Black (standard), Desert Tan, and OD Green. Note: 3RS 20" Shock Racks do not come standard with wheels; please see the 3RR-RCB Shock Rack Caster Platform in the accessories tab for an alternative.