The fourth element mask strap has been made using 100% recycled materials; The elasticated strap is made using rubber and recycled nylon; the clips are made from recycled waste ABS (Acrylonitrile butadiene styrene) plastic from the automotive industry. The clips have been designed so that they will fit most mask buckles, and will fit all fourth element masks. Made with 100% recycled materials Wide, comfortable, easily adjustble band Packaged without plastic Materials Strap: 100 % recycled polyester Clip: 100 % recycled RPET