ACDelco 49AGM Professional AGM Automotive BCI Group 49 Battery High density negative paste, improves performance and increases battery life Enhanced life alloy/Silver Calcium stamped alloy increases cycle life and improves performance Calcium Lead positive grid, maximizes conductivity and allows for low resistance Robust Envelope Separator with puncture-resistant back, allows for increased acid circulation and prevents shorts. Improved acid circulation, helps the battery to remain cool, and extend battery life. Vent cap design that resists acid leakage