This part fits your Unit Heater
Piston
Genuine OEM Part - Manufacturer #13101-ZA8-000
This part fits your Unit Heater
Piston (0.25)
Genuine OEM Part - Manufacturer #13102-ZA8-000
This part fits your Unit Heater
Piston (0.50)
Genuine OEM Part - Manufacturer #13103-ZA8-000