or do-it-yourself foam, rackmount rails for installation of 19-inch rackmount equipment, shock mounts for an internal rackmount frame, Retractable handles which are protected in some regard during shipping, airtight seal when the lid is closed and latched down, atmospheric pressure equalization valve , nitrogen filler valve, humidity indicators, wheels or casters, wheels and an extensible handle similar to a pull-around suitcase, legs to allow the removed lid to be used as a desk, and environmental controls: air conditioners, heaters or fans. Construction The principle design of a transit case is to assure environmental sealing and protection for the contents in adverse circumstances. Thus, construction techniques that provide seamless components (body, lid, end caps) are primarily used: rotomolded and thermoformed polyethylene, rotomolded LLDPE thermoplastic, deep drawn aluminum, fiberglass reinforced thermoset composites, FRP composite (fiberglass reinforced polyester), carbon fiber composite, carbon fiber / Kevlar composites, laminated materials (mostly used on road cases) Standards ATA 300 for airline transportation survivability MIL-HDBK-304C - Package Cushioning Design MIL-P-116 - Preservation methods MIL-STD-130 - Marking or printing identification data MIL-STD-648D - Design Criteria Standard Specialized Shipping Containers MIL-STD-810F - Environmental test methods and engineering guidelines MIL-STD-1367A - Packaging, Handling Storage and Transportability Program Requirements for Systems and Equipment MIL-STD-1472 - Human Engineering MIL-STD-2073-1D - Standard Practice for Military Packaging MIL-T-4734 - Transit Cases, Combination Cases and Spare Parts Cases for Ground Electronic Equipment Fed Test Method Std 101 - Test procedures for packaging materials See also Road case References Shipping containers