Genuine Casio G-Shock watch post and screw, one of each, for the band. 

Will fit at the 12:00 hour position (top) of the following models:

GW-500   GW-510

GW-530   GWM-500

GWM-530

Will fit at both 6:00 and 12:00 hour positions (top and bottom) of the following:

MTG-900  MTG-910

MTG-920   MTG-930

MTG-960