Mighty Max Battery 12V 18AH GEL Replacement Battery for FM12180 Rechargeable Sealed Gel 12180 Backup Power Batteries in the Device Replacement Batteries department at Lowes.com
BatteryGuy 12V 18AH SLA Replacement Batteries for Draeger Medical Evita 2 Dura Ventilator (External) (Pack of 2) - rechargeable - Walmart.com
Amazon.com: ML18-12 - 12V 18AH CB19-12 SLA AGM Rechargeable Deep Cycle Replacement Battery : Health & Household