...Clocks Hourglasses Sand Timer for Teeth Brushing Features 1. Applied to brushing teeth timer with 3 min hourglass, for dental clinic gift. 2. Materials: sand + glass + Plastic Application decoration or gift Type Hourglass Material plastic+glass+sand Color 1/2/3 min Sand...
...Clocks Hourglasses Sand Timer for Teeth Brushing Features 1. Applied to brushing teeth timer with 3 min hourglass, for dental clinic gift. 2. Materials: sand + glass + Plastic Application decoration or gift Type Hourglass Material plastic+glass+sand Color 1/2/3 min Sand... more
... balls and a narrow connecting pipe. Time is measured by the time it takes for a glass ball filled with sand to flow from the top through a narrow pipe to the bottom glass ball. Once all the sand has flowed to the bottom glass ball, the hourglass can be
... balls and a narrow connecting pipe. Time is measured by the time it takes for a glass ball filled with sand to flow from the top through a narrow pipe to the bottom glass ball. Once all the sand has flowed to the bottom glass ball, the hourglass can be more
