User Manual for Casio Watch Module - MY G-SHOCK News Casio Watch Manuals. This reference library contains over 1,500 Casio watch manuals. You need to look up the module number of your watch to find the right one. It should be engraved on the case back. Find that number in the list below to view the owner's guide and instructions for that watch. my g-shock wristwatch blog, news, and reviews MTGM900DA-8 - G Shock | Casio USA Casio's MTGM900DA-8 is from the family of G Shock. As an upgrade to it's predecessor, the new MTGM900 add the ability to connect with the radio transmitter in China to update the watchs' time & date in addition to adding an additional 18 cities added to the world time mode, for a total of 48-cities.