F-91WM-1BDF This Casio F-91W Series model features a black resin band with a matching black resin case and bezel, paired with a dark grey digital face for a clean minimalist retro look. Built with resin glass and water-resistant construction, its slim 8.5 mm profile and lightweight 21 g design make it comfortable for everyday wear. Confirmed functions include a 1/100-second stopwatch, daily alarm, hourly time signal, auto-calendar, 12/24-hour format, and green LED light, making it a practical everyday digital watch with understated black-and-grey styling.