Mighty Max Battery Replaces NP18-12 51814 6FM17 6-DZM-20 6-FM-18 Rechargeable Sealed Lead Acid 12180 Backup Power Batteries in the Device Replacement Batteries department at Lowes.com
LW-6FM17 Long Way replacement SLA Battery (12V 18AH)
Continental Replacement Battery for Enduring 6FM17 6-FM-17 12V 18Ah NB Sealed Lead Acid