This part is an ATO fuse for air conditioners and generators. A fuse breaks the circuit in the event that there is a fault in the machine that results in too much current to flow. It protects the machine from damage, and will burn out when activated. It may also break due to exposure to the elements.A new fuse may be needed if there is a gap in the wire or if there is darkness inside where the fuse has burned due to an overload. The user can also use a multimeter to measure the resistance of the fuse element to determine if it has gone bad. If the fuse is replaced and immediately goes bad, additional diagnostics should be done to determine the cause.The ATO fuse is a genuine OEM part from the manufacturer and is sold individually. This fuse is compatible with air conditioners and generators that are manufactured by the Generac and Carrier brands.