The Battery Tender Battery Charger 021-0128 is a compact and versatile charger designed to keep your battery fully charged and maintained. It is compatible with a wide range of 12-volt lead-acid batteries, including flooded, gel, and AGM types. This charger utilizes a 4-step charging program to ensure safe and efficient charging, and it also has a built-in microprocessor that constantly monitors and adjusts the charging process. The 021-0128 model features a quick connect harness for easy and convenient use, and it also has reverse polarity protection to prevent damage to your battery. With its compact and lightweight design, this battery charger is perfect for use at home or on the go.