Tap the lid and it tells you how hot your tea still is, which saves a nasty surprise on the train. The double-wall stainless steel body keeps drinks hot for up to twelve hours or cold for up to twenty-four, and the outside never sweats or scalds. It holds 500 ml, with a removable strainer for loose tea or fruit slices and a lid that seals properly inside a bag. The display battery is built in and lasts for years of daily taps. Hand wash the lid; the body takes a bottle brush easily.