Shrink Film is plastic that is heat sealed around an object or item that is being packaged. This loosly wrapped plastic is then hit with heat either from a heat gun or a heat tunnel. The plastic has additives that allow it to shrink when heat is applied. The plastic then forms around the product and the process is completed.
Shrink Film comes in a variety of widths, gauges and lengths. Please see the below chart for the size that best suits your needs.

60 gauge = 4370 feet per roll, 75 gauge = 3500 feet per roll, 100 gauge = 2620 per roll.