The Sun-Mar® Centrex 3000 is an extra-high capacity unit designed for very heavy cottage use or heavy residential use. The Centrex 3000 is a electric unit for those who have a continuous 110 volt power supply. All Sun-Mar® composting toilets incorporate a patented Bio-drum™ which ensures fast and odorless decomposition and saves thousands of gallons of water, while recycling waste into safe usable soil. The unit is shipped fully assembled and is used with either a Sun-Mar dry toilet or an ultra low water flush toilet (sold separately). When used with a Sun-Mar dry toilet a seperate A/F Waterless kit is required. Seasonal capacity: 9 adults or families of 11. Residential use: 6 adults or families of 8.