What is this glass object for? I inherited a bar set. It has a wide variety of glassware, all of which I recognize except this piece



The bottom portion holds a 1/2 cup. There is a small hole connecting the top and bottom. The top section is about 2in in diameter with a 3/4 inch opening between the top and the bottom. It is awkward to pour out of it and impossible to drink out of it. There are 12 of them, along with all the other glassware.

There are no markings on the glassware or the bar itself. The bar only contains liquor glasses (Collins glass, cordial glass, old fashion glass, shot glass) and no wine glasses or beer glasses.

What is its purpose?
It's a double bubble shot glass designed for a shot (on top) and the chaser of your choice on the bottom.  It is just a novelty and fancy way of presenting special drinks.  



Here's a video showing how it's used.