The DN01 Sunamp Optimino Heat Pump Key, compact at 25mm x 25mm x 15mm, ensures seamless integration between your Thermino xPlus unit and Daikin Altherma 3HHT R32 series heat pump, facilitating efficient heating solutions. Features & Benefits: Sunamp Optimino Heat Pump Key – Daikin Measures 25mm x 25mm x 15mm Enables seamless integration between your Thermino xPlus unit and a Daikin Altherma 3HHT R32 series heat pump Facilitates efficient heating solutions Enhances overall system performance