B5000D refers to a Full metal G_SHOCK Digital watch, specifically the GMW-B5000D series, which features a stainless steel construction with shock resistance, 200-meter water resistance, Tough Solar power, Bluetooth connectivity for smartphone linking, and radio-controlled timekeeping. These watches are a modern homage to the original G-SHOCK design, built with advanced engineering for enhanced durability and functionality, according to the CASIO website.