 Optima Blue Top Batteries Optima Blue Top Batteries are deep cycle batteries (with the exception of the 34M) and are designed for marine applications. Deep cycle batteries are designed to handle deep discharging between charges. |  Optima Yellow Top Batteries All Optima Yellow Top Batteries are deep cycle batteries and are designed to handle deep discharging between charges. |  Optima Red Top Batteries All Optima Red Top Batteries are SLI (Starting Lighting and Ignition) batteries meaning they are designed to stay mostly charged and are not meant to be deeply discharged. |