Mighty Max Battery Sealed Lead Acid AGM Battery, 12V, 55AH 22NF Rechargeable Sealed Lead Acid 12550 Backup Power Batteries in the Device Replacement Batteries department at Lowes.com
6V 1.3AH Lead Acid VRLA Rechargeable Battery - AliExpress
UPG 6-Volt 4.5 Ah Sealed Lead Acid (SLA) AGM Rechargeable Battery UB645 - The Home Depot
Lead Acid Battery: Working, Construction and Charging/Discharging