The VF01 Sunamp Optimino Heat Pump Key, compact at 25mm x 25mm x 15mm, ensures seamless integration between your Thermino xPlus unit and your boiler, facilitating efficient heating solutions. Features & Benefits: Sunamp Optimino Boiler Key: – Measures 25mm x 25mm x 15mm – Enables seamless integration between your Thermino xPlus unit and your boiler – Facilitates efficient heating solutions – Enhances overall system performance