Tested both in the laboratory & by our 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&9679; Keep drinks hot for up to 8 hours or cool for 24 hours&9679; Thermally induced vacuum for optimum performance&9679; Stainless steel construction with copper coated inner wall&9679; One-touch & screw-in stoppers provided with each flask&9679; Sleek design with lid that can be used as a cup&9679; Conforms to British Standards for quality & safety 0.7 L 75 x 75 x 285 mm 503g