AGM stands for Absorbed Glass Mat (technology) The Odyssey batteries were all built for a purpose. Generally the smaller models were to suit applications that required a small frame case with big cold cranking output which is fantastic that they make such a thing but theres always a con to running a smaller battery with bigger cca. The con is low amp hour which means you'll run the battery flat quicker so if you wish to purchase a small battery you must make sure you keep it on a charger when not in use if you have any form of alarm/gps tracking/dash cameras or anything else similar.
The quality on Odyssey is fantastic, vibration resistant, the pulse cranking is very strong and the service can be very good if you look after them. This battery is perfect is a popular choice for those wanting to relocate their batteries with an option of a special made billet bracket to suit or run it beside a intercooler thats made sizing very limited | 
