When it was first launched the G Shock was developed to be the ultimate tough watch. Casio engineers followed a development concept called “Triple 10” aiming to create a watch that could withstand a ’10-meter’ free fall, have ’10-bar’ water resistance and a ’10 year’ battery life.
They reached 200 prototypes before they achieved their goal. To achieve this they used a hollow structure and floated the movement inside using cushioning at critical points.
Various G-Shock models have been flight qualified for NASA space missions. The one pictured is the DW-5600E.
Read about the history and development of the G Shock watch