Battery boxes are made of Hi-Quality 304-L marine grade stainless steel, TIG-welded and electro-polished for long lasting performance. Our standard battery boxes are available in 3 group sizes, #24, #27, #30/31, optional cover step plate and also with sealed lower containment box to prevent leakage into the bilge or environment. This containment model is made to NMMA standards. All Battery boxes come with a 10 year limited warranty.