To find the right battery, check four things:
Voltage Be sure to choose a battery with the correct voltage for your application. If you are replacing a battery, this should be readily apparent on the battery label. Common voltages are 6 volts and 12 volts.
Ampere hours (Ah) represent the battery capacity i.e. the electric charge delivered over time. As long as you choose the right voltage, you can use a battery with any Ah rating. Higher Ah batteries will deliver power for a proportionally longer time.
Dimensions Always confirm that the battery will fit in the space available for your application. Do this by measuring the length, width, and height of the available space and comparing them to the dimensions of the battery being purchased.
Terminal Be sure to purchase a battery with the right terminal for your application. Common SLA battery terminals include F1, F2, and NB.