FL-MT Glass by Merv Taylor
When filled, this 3 1/2" tall x 2" diameter glass will allow you to show it full and then empty it, without actually pouring any liquid from the glass. Quick as a wink, the glass immediately fills again.
This is a clever item from the 1950s, and is very well made of Lucite. Through the many years the liquid within has solidified a bit, so it's not as full as it used to be. This can be filled with some degree of work to either open the plug originally used to seal in the liquid or to drill a very small hole in the bottom and reseal. It is otherwise in good condition.
Includes illustrated instructions and original box.