Reclosable zipper bags can be used for many things such as packaging food, clothing, machine parts and many more purposes. It is made from LDPE (Low density polyethylene) and have a hanging hole at the top of the bag. It comes in 2 different thicknesses 2 Mil, and 4 Mil. The 2 Mil is standard poly thickness, but if you think you need some extra support, then we would suggest going with the 4 Mil. There is also an option for a white Block on some sizes, which will allow you to write on the bag with a pen or marker.