Battery Box Mount Kit Universal Fit Plain Cast Aluminum Hold Down Hardware. Universal Fitment: Designed to mount standard automotive batteries in a wide range of vehicles, providing a secure base for street rods, hot rods, race cars, and custom builds. Premium Construction: Robust cast aluminum box and hold-down plate deliver corrosion resistance and durability for long-lasting performance in engine bays. Complete Mounting Kit: Includes all mounting bolts and hardware needed for a straightforward installation, saving time on fabrication or modification. Ideal Battery Size: Internal dimensions approx. 6-3/4? × 10-1/4? Accommodate many common battery sizes with secure hold-down to minimize movement during driving. Custom Project Essential: Perfect for restoration projects, custom chassis builds, or relocated battery installations to tidy engine compartments. Complete kit with bolts and cast aluminum top hold down. Inside measurements are 6-3/4″ x 10-1/4″. Outside dimension of lid is 7-7/16″ by 11-1/16″ Length to outside of hold down flange on lid is 12-7/8 This box will accept all of the Optima batteries with a very minor bit of grinding on the bottom mount flange of the battery. 14 x 8 x 7 inches.