Replaced the 394 module in my vintage MD-700 to bring it back to life. A bit small by modern standards, but a common men's size in the past. : r/ casio
Casio MD-502 Battery Change
RARE! Casio Diver MRD-201W (394) JAPAN C White Dial Men's Watch NEW BAND/SEAL! | eBay
Casio 394 MD 770 for $141 for sale from a Trusted Seller on Chrono24