Hot air welding technology Bottom Block Valve Bag ISO9001:2021 pp bag manufacturer Bottom Block Valve Bag1) Made by polypropylene2 ... hot air welding, starlinger brand machine NameBottom Block Valve BagStyleblock bottomWidth55cm or as customer's requestLength75cm ... high technology--hot air welding technology,quick delivery, competitive price, good service, multiple usage PP Woven Block Bottom Valve ...