It is a clear plastic bag with items, when heated,will shrink.
The most commonly used shrink wrap is polyolefin.
Best explanation of Shrink wrap From Wikipedia:
Shrink wrap, also shrink film, is a material made up of polymer plastic film. When heat is applied, it shrinks tightly over whatever it is covering.
1) Heat can be applied with a handheld heat gun (electric or gas),
2) or the product and film can pass through a heat tunnel on a conveyor.
Here is the heat shrink wrap machine with sealer parts for your reference:
shrink wrap machine for egg box:
Heat shrink tunnel machine for food bottles:
Heat tunnel machine for a box or carton wrapping:
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