UPDATE: Never mind. I finally found the information I needed on the SuperMicro website. “All of our MBs use coin cell CR2032 CMOS batteries that are ~ 20.0mm(Dia) x 3.2mm(H).”
My (new to me) secondhand Supermicro h12ssl-i motherboard arrived today sans battery. I assume that all motherboards use CR2032 batteries but… Is this a correct assumption on my part?