Miata / MX5 enthusiasts will love this lightweight racing inspired Aluminum battery box.  It is available in either a raw Aluminum finish or black powder coat finish.  It is designed to either fit in the engine compartment -or- can easily be used in the trunk.  It is designed to work on any Group 51 size battery.  It features two heavy duty straps to secure the battery in the box.
 
Battery box measures:
10 inches long
5-1/2 inches wide
6 inches tall