The Rolls Surrette 4KS21PS (4-KS-21PS / 4KS-21PS) is rated at 1104 amp Hrs. @ 20 Hr. rate. The 4KS21PS (4-KS-21PS / 4KS-21PS) is a practical expansion of the Roll's New Generation Dual-Container 4 Volt line. Using the famous Rolls Surrette KS plate, this battery offers higher capacity and less watering due to fewer cells per string. The KS plate batteries have a reputation of 15-20 years expected life. Warranty is 10 years (first 36 months replacement, next 84 months pro rated). For a Single String 1104 AH Bank, you will need 3 of the 4KS21PS (4-KS-21PS / 4KS-21PS) for a 12 Volt System, 6 of the 4KS21PS (4-KS-21PS / 4KS-21PS) for a 24 Volt System and 12 of the 4KS21PS for a 48 Volt System. Each additional string will multiply the AH.