The Professional Classic Series Direct Vent Co-Axial water heaters are optimized for manufactured housing, boasting .58 - .60 UEF efficiency and offering capacities of 40 and 50 gallons. Designed with a focus on space-saving and efficient heating, these units ensure reliable hot water supply while meeting specific housing requirements. With their co-axial venting system, they provide a compact and effective solution for residential water heating needs.