Attwood Heavy-Duty Acid-Resistant Power Guard Series 27 Vented Marine Boat Battery Box Black. When it comes to protecting your Series 27 battery you can?t beat the Power Guard. It combines acid-proof materials with performance specs that meet or exceed U.S. Coast Guard standards. Vented design with comfortable rolled-edge handles. Attwood Corporation has been an award-winning leader in engineering testing and manufacturing the highest quality marine products for over 100 years. We deliver safe and reliable lighting fuel systems water systems seating & pedestals swim ladders custom upholstery and general marine accessories that are easy to install and meet regulatory compliance.