Box: Box (插座)
The receiving body at the lower end of an open-end zipper into which the insertion pin slides. The internal channel and retaining lips position the pin and hold both tapes together when the zipper is open. Box dimensions must match the pin and slider gauge; poor fit produces hard insertion, weak retention or accidental separation. Boxes are die cast in zinc alloy or moulded in POM and are assembled with the pin during finishing.