Fully Automatic - Designed to maintain 12 volt batteries up to 250 amp hours Increase Performance - Precision regulated 13.4 VDC float mode Can be left on for extended periods without overcharging or damaging batteries LED status indicator User adjustable for gel's Built-in Safety - Reverse polarity protected-Certified to U.L. 1236 Marine Size: 2.2" L x 3.5" W x 3.9"H 4' Cable length