9 x 12" Poly Bags On a Roll are great for high volume packaging operations. 1 Mil thick. Bags come on an industry standard core allowing for compatibility with all automatic packing equipment. Roll changes from 1" to 3". Bags have one end that is pre-opened and one end that is sealed. Bags are manufactured from 100% virgin film and are perforated for easy tear-off. Bags meet both FDA and USDA specifications. Bags can be closed with twist ties, impulse sealers, or bag tape.