Never again worry about over-filling your beverage glass or coffee mug. Simply hang the handy Vibrating Liquid Level Indicator on the lip of your cup or glass and pour with complete assurance. The indicator will vibrate to alert you when the liquid level nears the top, preventing accidental over-filling and messy spills. Pocket-sized for easy transport. Uses one 9-volt battery (included.) Great tool for the Blind, Deaf, Blind-Deaf and Low Vision.