Each of these 4 mil. Pre-Opened Bags on Rolls are made of 100% virgin Low Density Polyethylene (LDPE) resin that meets FDA/USDA specifications. Pre-opened bags on rolls are for use on automated packing machines. Available in clear or white front/clear back styles. Made with tubular construction and durable bottom seal, these bags have an open slit in the front and a perforated back for automatic or fast hand loading. Wound on 3" Cores.