Group 31 with brass SAE posts, 3/8 inch positive and 5/16 inch negative thread SS stud terminals, and single external vent. Attachment hardware for stud post is included with the battery. 

Like an athlete that is both a sprinter and a long-distance runner, the ODYSSEY Marine Dual Purpose battery has both massive starting power and amazing deep cycling capability - up to 400 cycles at 80% depth of discharge. With twice the overall power and three times the life of conventional marine batteries, the ODYSSEY battery is ideal for trolling, starting, and for powering the many on-board electronic accessories common in today's boats and recreational vehicles.

This is a great starting or reserve battery for larger boats and yachts.