The CTEK M300 (25A) is a powerful and complete 8-step, fully-automatic, switch mode battery charger that analyzes, looks after, charges and maintains all types of boat batteries. The M300 is designed to take care of your service batteries and the M300 STARTER offers a constant maintenance battery charge for the starter battery. The M300 has been specially developed to make boat life safer and more convenient for today's boat owners.