This custom made carbon fiber battery box weighs in at only 6 oz. and is unbelievably strong. The box walls are a mere .020" thick carbon. Inside dimension is 10-1/8" to accommodate stock and 'Optima' style battery. It is impervious to corrosion, rust and acid. It fits snugly under the spare tire in the front compartment, leaving the entire battery area in the engine compartment free and clear for ignition electronics.