The first G-Shk, the Casio DW-5000C, was designed in 1983 by an engineer working for Casio named Kikuo Ibe. It was designed to have a 10-year battery life, be water resistant to 10 bar, and survive a 10m fall onto a hard surface. 200 prototypes were tested by dropping them from rooftops or third story windows. The shock resistant design has 10 layers protecting the quartz timekeeping module, including a urethane rubber bumper, the stainless steel case, the hardened mineral glass watch crystal, the stainless steel screwed down caseback, and the "floating module" where the quartz mechanism floats free in a urethane foam cradle, with the outer buttons and LCD module attached with flexible cables, It was released in April 1983, seizing the unfilled market for highly functional watches. For the next few years Casio released several new models each year. The Baby-G series was released in 1991, targeted towards women. The popularity of G-Shk increased rapidly throughout the 1990s, and by 1998, 19 million G-Shk had been sold worldwide and there seemed to be a peak in demand as over 200 new models were released in that year alone.