The original announcement from Casio said they'd be making a ring version of the venerable DBC-611 calculator watch as well: https://www.g-central.com/casio-to-release-casio-watch-ring-...
It looks like they've instead made a ring version of the CA-53W, which - in the staggeringly few times I see someone wearing a calculator watch - is usually the one they're wearing.
I still wear a DBC-610 as my daily driver, and I do use the calculator and countdown timer features quite often.
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