An internal frame mounted on adjustable elastomer shock absorbers on all eight corners. These revolutionary shocks are designed to control the effects of shock and vibration on three axes. The "sway" space around the internal frame provides natural air conditioning -- very important for delicate equipment. Inner rack chassis depth is 20" rail to rail with pre-threaded rack rails for standard 10-32 hardware that is included. They are half the weight of the old wooden cases. Features Rear rails Shock resistant Optional caster kit Roto molded for strength Adjustable elastomer shock absorbers Molded-in handles provide secure grasping points Interlocking X-pattern for solid stackability Front and rear full size lids Recessed latches Shock absorbing feet Specifications Exterior Hard Built In Shocks Yes Rack Units 8 Front Rail To Back Lid 23.875 in 60.64 cm Rail To Rail 19.875 in 50.48 cm Rear Rail to Front Lid 23.875 in 60.64 cm Product Weight 50.3 lb 22.81 kg Exterior Length 29 in 73.66 cm Exterior Width 27.5 in 69.85 cm Exterior Height 22.375 in 56.83 cm Carton Length 29.5 in 74.93 cm Carton Width 28.5 in 72.39 cm Carton Height 23 in 58.42 cm Shipping Weight 55.85 lb 25.33 kg