Bag Closing with a closure may be with either a wire twist tie or a piece of tape.
Tape:
Bag Sealer with tape. Good for low production but your customer may have difficulty re-closing the bags with the same piece of tape.
Twist Tying:
The second method of closing the bag is to use a Wire Twist Tie Machine. Similar to the twist tie found on loaves of bread at the grocery store. Twist tying machines are available in 3/8", 5/8", 7/8", and 2" models.