Oddball MT920 battery. See more in comments. : r/CitizenWatches
Battery MT920 rechargeable | Horlogeband.com
Citizen 295-69 Capacitor (MT920 Base cell with Tabs - Secondary Battery)
Genuine Citizen Capacitor 295-29 DIY Kit with free Tools - Capacitor Solar Watch Group - Watch Batteries - AA AAA batteries - Rechargeable Batteries - Discount Batteries - Shipped Free in US
Amazon.com: Genuine Replacement for Panasonic MT920 "HAS NO METAL TAB / CONNECTOR" Lithium-Titanium recharable Battery Cell #10212754 for Casio Solar Powered & ETA Watches #10233316 w/ No Connector : Health & Household