Or Tea? T’mbler is designed for you to enjoy your tea on the go whether it is cold or hot. Made in high quality stainless steel printed with our signature Or Tea? Illustrations. Each T’mbler comes with a smart thermostat installed in the lid to track the temperature of the tea in the flask. No battery is required as it has a lifetime of on-off for 50,000 times. A strainer is also provided for loose tea lovers.