Super Rare Casio F-15 Blue/Red model 1988, the brother to the white model, equally as rare, this is 1 of only two I've ever seen and is used but in great condition. :
Casio Classic - help identifying! | WatchUSeek Watch Forums
Casio F-15 black by glrvod - Haylou Solar LS05 | 🇺🇦 AmazFit, Zepp, Xiaomi, Haylou, Honor, Huawei Watch faces catalog
Case for CASIO Vintage SOLAR W-15 // Only CASE & CaseBack | eBay
Microchip SAM L22 board makes Casio F-91W watch more customizable (Crowdfunding) - CNX Software
Amazon.com: Casio F91W-1 Classic Resin Strap Digital Sport Watch : Clothing, Shoes & Jewelry