Light in weight yet tough enough to be almost unbreakable, this flask has an easy-grip handle and a stainless steel cap that doubles as a cup. The double-walled vacuum insulation keeps hot drinks hot and cold drinks cold for longer. Looking after your flask For safety and hygiene, clean your Thermos product with warm water and washing-up liquid prior to initial use. For best results, before each use, pre-fill for about three minutes and then empty, using either hot water for hot drinks or cold water for chilled drinks. Never use a microwave or conventional oven to pre-heat the flask. If it hasn't been used for some time, rinse with warm water to remove any residual odours. Do not immerse it in water or overfill it. Store it with the stopper off. For difficult stains, put a teaspoon of bicarbonate of soda in hot water with the stopper off. After filling, always ensure that both the outside cup and stopper are tightly closed.