Battery Box, Sized For Marine Group 27/31 Batteries, 13-5/8" x 7" x 8", Made Of Polypropylene, Same Material As The Battery Case, Is Tough & Impervious To Battery Acid, Vented For Safety & Included Space For Cables, Lid Is Held In Place By Acid Resistant Strap & Buckle, Included, Spacer Included To Accept Both Battery Sizes.