The serial number is engraved on the motor housing of the nailer. It is on the right side (battery compartment side). The easiest way to locate the number is to hold the tool with the battery side up and the nose pointing to your right. Look approximately 1 inch below the “P” on the Paslode label and toward the handle. On the CF325 it is located below the nose of the nailer. The serial number is 9 or more digits long.