Two sizes available, 3.7kwh is the standard size and is what comes with the SP140 by default, and is the the recommended size for high thrust setup, or heavy tandem flights. The 2.2kwh battery is the half-size option. The 2kwh battery is 12lbs lighter and around 1/2 hour flight times.
Note- This is the new version battery with soft switch and new connector. If you are looking to get and extra battery for your SP140 V1.1 or V1.0 you will need to get an adapter for the connector.