O-ring sealed with an Automatic Pressure Equalization Valve and it is watertight, crushproof, and dust proof. The 1720 will keep your firearm protected inside its strong, lightweight open cell core walls and packed tight in a three-piece foam set. For portability, the 1720 is equipped with polyurethane wheels and fold-down handles. Interior measures 42" x 13-1/2" x 5-1/4". Exterior measures 44-3/8" x 16" x 6-1/8". Lifetime Guarantee of Excellence.