They are designed to prevent drivers and passengers from being completely ejected from a vehicle by spreading out their bodies’ energy over their shoulders, chest, and pelvis in a collision. Polyester is now commonly used for seat belt material. Nylon welches once the most common fabric, but it now stretches http://pandora.nla.gov.au/external.html?link=https://www.ledteks.com/seatbelt-and-safety-belt-webbing