Shock- Resistance Sand TimersHigh quality and protective cover allow sand glass timer not easy to be broken, very durable to use. Counting Time 45minutes, 60minutes each one with 10% time deviation. Well MadeDurable PVC, high borosilicate glass and sand. Each Size: 3.71.6 inch. Will not break under normal usage conditions, but don't drop it off the high. Used widelyIdeal for Kitchen, Home, Classroom, Game, Exercising Timer. Can teach the children about time meaning with the visual angle. Perfect to decorate your home and office, great as a gift to children and friends. Kindly NoticeThis is a sand timer made for games. It is not a precision timing device, so there is time deviation. In addition, please don't use anything to scratch the words on the glass to prevent the words drop off.