The Booster transformer allows installation of an iCombi Pro or Classic 20 full gas 208/240V models on 120V receptacles. The Booster is pre-wired for plug and play installation between the 120V receptacle and the iCombi. The iCombi must be set to 240V by trained technician at time of installation / commissioning. THIS ITEM IS NON-DISCOUNTABLE, USA ONLY (NET)