Mercury - Bravo Three 300-Hour Maintenance Kit MerCruiser Sterndrive Service Complete Marine Components 8M0215917. Overview. Anyone who's spent enough time on the water knows that a smooth-running sterndrive isn't an accident. It's the result of steady, thoughtful maintenance-the kind that gives you peace of mind when you throttle up, trim out, and settle into a long run. This Mercury Marine part brings that reassurance back to your Bravo Three. Everything you need for a proper 300-hour service