basically a polyurethane foam that included a small amount of dilatant. This resulted in a non-Newtonian compound that was soft, pliable and comfortable to wear, but hardened instantly on impact to absorb the force applied in a fall. It then immediately relaxed to its former state. This made it ideal for the purpose of preventing hip fractures where the device has to be worn 24/364. Patient compliance was always the main problem with hip protectors as they were usually too uncomfortable and/or hot to wear in bed, nighttime being one of the most dangerous times in terms of falls. No longer. Fall-Safe is worn all the time.