Pre-opened bags on rolls are for use on automated packing machines. 

You'll find 6 different sizes of 2 Mil Pre-Opened White Front / Clear Back Poly Bags on Roll. Stock items ship within 24 hours.

Made with a tubular construction and a durable bottom seal, these bags have an opened slit in the front and a perforated back for automatic or fast hand product loading. Pre-opened bags are neatly wound on 3" cores. 

Sizes are shown as W x L in inches. Prices are per roll.