Behold the HM3 Frog Zr, aka “Black Frog,” the newest highly limited watch from MB&F – there will only be 18 pieces. Unless I am mistaken, this is the first watch offered by the boutique brand done in zirconium (hence the Zr part of the name). Zirconium is a rare metal similar to titanium, but known to be more robust. According to MB&F, most zirconium is used in nuclear reactors and high-tech aerospace applications. There are a few high-end watches that utilize the exotic metal, and now MB&F has an interesting piece imbued with Zr.