Compatible with the Baxi EcoBlue System Boiler only. An outdoor mounted weather compensation sensor works with the boiler to give fuel savings and improved comfort levels in the home. Offers increased SAP benefits for specifiers. No controls or settings for ease of use. Includes relay box. Compatible with the Baxi EcoBlue System Boiler Only Sensor Operation For External Use Easy to Install 1 Year Guarantee Easy to Use Reduces Cold Water Consumption Reduces Carbon Emissions Comes with Relay Box Compatible with the Baxi EcoBlue System Boiler Only Sensor Operation For External Use Easy to Install 1 Year Guarantee Easy to Use Reduces Cold Water Consumption Reduces Carbon Emissions Comes with Relay Box