These battery trays are designed to have the absolute smallest dimensions possible for mounting batteries in tight spaces. These trays eliminate 1.5" - 2" of space when mounting trays side by side. This space saving was accomplished by eliminating the external mounting tabs and moving the mounting holes into wells enclosed in the tray walls. Molded of acid proof polypropylene and available with poly strap hold down or rod hold down. Meets NMMA specs for battery retention.