Function: It is a device used to measure the passage of time by allowing a regulated flow of fine sand from an upper glass bulb to a lower one through a narrow neck.
Design: The specific item pictured has a brass-tone metal frame that allows the glass timer to swivel or rotate, making it easy to flip over to measure another time interval.
Usage: These timers are often used for decorative purposes, as time management tools for tasks like homework or games, or as vintage gifts.
Material: The main components are the metal frame (likely zinc alloy with an electroplating process) and hand-blown glass bulbs.