For those who travel at Mach speed, Hamilton’s got a watch that measures aircraft speed through the air, divided by the speed of sound. The appropriately-named Khaki X-Mach allows pilots to set pressure altitude and calibrated air speed on the watch’s crown, bearing a measurement in International Standard Atmosphere conditions. For the rest of us, the Khaki X-Mach merely looks like a flying instrument, with metal and carbon fiber construction accented by flying jacket-style stitching and studs, a Clous-de-Paris guilloche pattern around the date and hints of red to complement the sporty charcoal gray. Sapphire crystal protects the time-telling instruments, and the watch is water-resistant to 100 meters. It’ll set you back by $1,645, which is at least cheaper than a jet plane. [via InfoNIAC]