Amazon.com: AJC Battery Compatible with Long Way LW-3FM4 6V 4.5Ah Sealed Lead Acid Battery : Health & Household
Mighty Max Battery Replaces cp0660 gp645 lcr6v4p hk-3fm4.5 wp4-6 Rechargeable Sealed Lead Acid 645 Backup Power Batteries in the Device Replacement Batteries department at Lowes.com
BatteryGuy BG-640 6V 4AH Replacement for Hong Kong HK-3FM4.5 (2 Pack, rechargeable)
Amazon.com: BatteryGuy HK-3FM4.5 Replacement 6V 4.5Ah SLA Battery Brand Equivalent (Rechargeable) - Qty of 1 : Health & Household