Heavy gauge steel construction holds up in applications where plastic units just wont do, either for durability reasons, or when materials being stored are not compatible with plastic. Welded steel bar grating is removable for easy clean-up. Drip channels hook units of same heights together, help prevent drainage between units. Optional ramps available in 2 heights. All models help you comply with EPA and OSHA requirements; models with 66 and 99 gallon capacity help you comply with Uniform Fire Code.