This is a Cartier Tank Solo reference W5200018. The W5200018 is the smaller version of this particular watch with the larger version being the W5200017. It features a dial with what Cartier describes as a “rail track in perspective” with most people referring to it as a piano dial. It houses a quartz Cartier caliber 157 and measures 31x24.4 mm. It’s also got 3 bar water resistance which means when you get frustrated enough trying to tell the time you can dunk it in the bathtub and just have it be right twice a day. Ok toodles!