Casio] W-800H. Modified to have a countdown timer function!!! : r/Watches
Casio W-213 — Countdown Timer with Auto Repeat & 10-Year Battery Life
Amazon.com: Casio Mens G-Shock Digital Watch, with Shock Resistant, Quartz Digital Movement, Stopwatch, and Countdown Timer, Auto Calendar, Backlight with Afterglow, Water-Resistant to 200 M (660 Feet) : Clothing, Shoes & Jewelry