YUASA NP18-12B, 12v 18Ah Valve Regulated Lead Acid (VRLA) Battery. (12V 18Ah). YUASA CODE: NP18-12B. Low pressure relief valve. Fully Sealed (cannot spill) - Rechargable - Deep Cycle battery. For standby power this range has a nominal 5 - 8 year life.
eBay