Speaker sets come in all different shapes and sizes, so this concrete speaker set falls right in line. The set is made of real concrete, but rather than just throwing a rock and some wire together, the makers opted for a little bit more finesse.
The concrete aspect in the concrete speakers is reinforced by glass to make it not only stronger, but more stable. Because it's made of concrete, it can fall victim to many of the same things that affect concrete over time. Things like water, acid and citrus juices can all deteriorate the material, but considering that you wouldn't want those things getting close to any of your speaker sets, it should be fine.