Held it up to my ear and shook it, can hear the liquid inside.

Only concern from the design, it flows and cools the bottom of the glass, not the top.

Good product quality, fast shipping, full warranty

Thought they would be heavier, light what

They showed themselves perfectly in the case. 3 cubes quickly cool a glass of Martini from room temperature to a palpably cool. Much more effective than ice and without dilution with tall water. Very pleased.