Keep your Massimo E-Kooler running, wherever your adventure leads. Up to 6 hour of additional run-time, under normal conditions. Fits All Massimo E-Kooler TWW and ENX models. (Does not fit CX model E-Koolers). Simply remove blank plate from your cooler, insert battery, and charge for extra cordless cooling power. Refer to E-cooler User Manual for charging instructions. Do not exceed 8hr charge time.