These containers are as strong as a plywood crate, but at the cost of corrugated! Perfect for shipping heavy items such as small motors, compressors or valves. Constructed from 1100#TW/ECT-90 kraft corrugated. Additional thickness provides extra protection, security and stability during shipment. Corrugated boxes are reusable and recyclable. Cartons are sold in bundle quantities and ship flat to save on storage space and shipping. Proudly made in the USA!