Tested both in the laboratory & by Lifeventures recent expedition to Baffin Island these are highly efficient insulating vacuum flasks. The Vacuum is created from a heating & cooling manufacturing process that is more reliable than many other flask designs. Features Keep drinks hot for up to 8 hours or cool for 24 hours Thermally induced vacuum for optimum performance Stainless steel construction with copper coated inner wall One-touch & screw-in stoppers provided with each flask Sleek design with lid that can be used as a cup Conforms to British Standards for quality & safety Capacity: 1 Litre Dimensions: 83 x 83 x 320 mm Weight: 570g