Bungee Cords have come a long way, including the Energy Suspension Power Band tie-down straps are designed to be elastic enough to stretch easily to holding points. Made of HYPER-FLEX polyurethane, they far outlast ordinary rubber tie downs. Each size band was engineered for its own requirements. They come with 3/16 in. diameter "S" hooks for added strength and the hooks are made of stainless steel to help protect against corrosion.