Comet Gray Wave Propane Cylinder features a unique three-part design for decreased weight and reliability. Each Comet tank features a steel liner that is strong, corrosion resistant and meets all filling station requirements. Surrounding the steel liner is a high-tech fiber wound composite material that protects the inner steel liner from impacts and abuse. The composite liner is both strong and corrosion-proof. The final layer of protection is a high density polyethylene jacket with built-in ergonomic handles for easy lifting that is dent and crack resistant. With three-layers of protection Comet tanks offers premium safety and protection for all your propane storage needs.