Mighty Max Battery ML1.3-6 6V 1.3AH SLA Battery F1 Terminal- 4pk Rechargeable Sealed Lead Acid 613 Alarm System Batteries (4-Pack) in the Device Replacement Batteries department at Lowes.com
6V 4.5AH SLA 1/4" FASTON REPLACEMENT BATTERY COMES IN SET UP TWO BATTERIES - NCE Empowering Safety
6V 1.2AH SLA Battery
BW 6v 4.5ah SLA Battery (Emergency Lights and Universal Use) – Battery World