It is common for a power tool system from a manufacturer to include a battery pack that is designed and configured to mate and operate with at least one power tool and a battery charger. However, as systems have evolved it has become desirable to provide a battery pack that is designed and configured to mate and operate with at least one power tool and a first battery charger but not a second battery charger. The present disclosure provides a battery pack including a housing, a terminal block, a plurality of terminals, and a mechanical lockout for allowing engagement with a power tool and a first battery charger while preventing engagement with a second battery charger.