Casio developed its first calculator in 1957, but it was not until 1974 with the release of the Casiotron that Casio entered the watch making a market. 

G-Shock is a brand of watches manufactured by Casio, known for its resistance to shocks (e.g. hard knocks and strong vibrations). Its full form is Gravitational Shock. They are designed primarily for sports, military and outdoor adventure oriented activity; nearly all G-Shocks have some kind of stopwatch feature, countdown timer, light and water resistance.

Product Features:

• Mineral Glass
• Shock Resistant
• 200-meter water resistance
• Case / bezel material: Resin
• Resin Band
• Electro-luminescent Backlight 
• Afterglow
• Flash Alert 
• Flashes with Buzzer that sounds for alarms, hourly time Signals.
• 1/100 Second stopwatch- 
• Measuring Capacity: 
• 00'00''00 ~ 59'59''99 (for The First 60 minutes). 
• 1: 00'00 ~ 23: 59'59 (After 60 minutes). 
• Measuring Unit: 
• 1 / 100 Second (for The First 60 minutes). 
• 1 Second (After 60 minutes). 
• Measuring modes: Elapsed time, split time, 1st-2nd Place Times.
• Countdown TimeR 
• Measuring Unit: 1 Second 
• Countdown Range: 24 hours 
• Countdown start time Setting Range: 1 Second to 24 hours (1-Second Description, 1-minute and 1-Hour Description). 
• Other: Auto-Repeat
• Multi-function alarm
• Hourly time signal
• Full auto-calendar (to Year 2099).
• 12/24-hour format
• Regular timekeeping: Hour, minute, second, pm, month, date, day.
• Accuracy: ± 15 seconds per month.
• Approx. battery life: 2 years on CR2016.
• Size of Case: 53.2 × 50 × 16.3 mm
• Total weight: 67 g