Not the first time I’ve seen something similar but this Kickstarter project for the stainless steel Pucs are by far the most well crafted. The general idea is ice cubes are terrible at keeping liquids cold. They immediately melt and dilute the flavor and they can even alter the taste if your water source isn’t pure from the start. Don’t even get me started on the chemicals used to treat city water supplies. Pucs stay colder longer and imbue no taste or smell to your drink.
Designers: Dave & Calvin Laituri, Kickstarter