Key Features: -10 ATM water resistance, support up to 100 meters (328feet) underwater operation. -Support stopwatch function. -Support countdown timer function. -Support alarm clock function. -Support hourly chime function. -Support dual time zone display. -12/24 hour format selectable. -Support month, date, week day check. -Negative electro luminescent backlight built-in. -Support shock resistant. Parameters: Time Accuracy: ±30 seconds per month Maximum Diving Depth: 100m Water Resistance Level: 10 ATM Countdown Range: 23:59'59'' to 0:0'0'' Watch Shape: Square Watch Movement: Digital Battery Code: CR2025 Operating Battery Life Time: 1.5 to 2 years Watch Dial Window Material: High Transparency Resin Watch Case Material: ABS Watch Dial Color: Black Watch Case Size: 36x36mm Case Thickness: 10mm Watch Strap Material: Silicone Watch Strap Color: Black Watch Strap Clasp: Pin Buckle Watch Strap Width: 20mm Maximum Wrist Circumference: 235mm Minimum Wrist Circumference: 130mm Note: The battery is replaceable. If you find that the watch is not working or the text on the display is not clear, please replace the watch battery in time.