Our Alpine Thermo Bottle 0.75 Litres is a thermos which has been strategically engineered with an inner chamber surrounded by a very thin vacuum. The construction of this thermos bottle creates a barrier to restrict heat transfer via conduction and convection. In order to reduce radiant heat loss, the inner chamber is copper plated to reflect heat back into your tasty beverage. Additionally, we have injected insulation into the cap to limit heat loss from the top of the bottle. In the harsh conditions of alpine surroundings, weight and ease of use become very important.