Function: These devices are used to measure the passage of time by allowing a regulated flow of sand from an upper glass bulb to a lower one through a narrow neck.
Design: The set features three individual timers within a single wooden frame, each with different colored sand (blue, green, and yellow).
Usage: Sand timers like these can be used for various purposes, including cooking, playing board games, as a teaching tool for children to understand time, or simply as a decorative item. The specific duration of time measured depends on factors like the amount of sand and the width of the neck.