Vmaxtanks VMAX MR197 12 Volt 200AH AGM SLA Marine Deep Cycle HI Performance Battery 20"*6.8"*9.6"h Heavy Duty 12V AGM DEEP CYCLE BATTERY with Float Service Life span of 8 to 10 years. Electrolyte Suspension system: VMAX tanks utilize an electrolyte suspension system consisting AGM (Absorbed Glass Matt) of a high porosity that totally absorb and contain the electrolyte. No silica gels or any other contaminants are used. Heavy Duty Grids: VMAX heavy duty lead tin alloys provide an extra margin of performance and service life in either float or cyclic applications, even after repeated over discharges. Maintenance Free Operation: There is no need to check specific gravity of the electrolyte or add water to VMAX tanks during float service life. In fact, there is no provision for this type of maintenance. Visit Manufacturer's web site for further info vmaxtanks.com