Vacuum removes air through one-way valve; Reusable, air and water tight and multi-layered; Sure-Zip? slider ensures airtight seal that keeps bulky items compressed; Set of 6 bags (different sizes)Sizes: Extra Large: 39 1/2"tall x 26 1/2"wide Large: 33 1/2"tall x 21 1/2"wide Medium: 22 1/2"tall x 18"wide;