Nice nineties G's, 5900 [1990-94] and it's five year younger brother 6900-1V [1995-01]. DW-6900-1V was so successful, skin and anatomy is still popular in the modern G6900 models. I own a pass down 1992 5900 and 1995 6900 with correct year of purchase. Definitely both have rendered vintage being 15, 20 or 25 years old.
Casio ceased production a long time ago so parts are hard to maintain. However they are worth lots especially the 5900. 5900 known to appears on Martin Lawrence wrist in Bad Boys. Both a certified NASA flight approved in ISS. Check out images below of my 5900, one with Nissan GTR in the background TV screen which is a good comparison like Skyline R32 to R33. I do believe they made Nissan G Shock's and also NISMO