The Casio 3171 IDF‑50 is a digital Casio watch using the 3171 module, likely closely related (or identical) in function to the Casio LDF‑50 / Poptone 3171 models. It offers standard digital-watch features (time, stopwatch, alarm, dual time, calendar) plus a light, all running on a CR1216 battery with an expected ~3‑year life. Its 50m water resistance makes it okay for splashes or light swimming (but not deep diving).