GreenVAC Vacuum Packaging Systems are an environmentally friendly reusable vacuum packaging system specially manufactured to provide a 99.8% vacuum seal to products sensitive to pressure, such a s berries and salad. Designed to be used with GreenVAC's 90311 External adapter hose and the Jumbo/Boxer Series or any appropriately sized vacuum chamber or vacuum pump (sold separately). Equipped standard with a vacuum lid, gasket seal and nozzle. Manufactured from 1.2 mm (17 gauge) and 1.5 mm (18 gauge) chromium-nickel steel. The transparent lids are made from a material called Grilamid, which is essentially a transparent polyamide that is processed using thermoplastic methods. All products are able to withstand dishwasher cleaning cycles at temperatures of up to 194F.