Cast iron body and wet rotor motor. Die-cast aluminium motor casing.Flanged inlet and delivery mouths, fitted with threaded unions for pressure gauges.Technopolymer impeller, tempered stainless steel driving shaft.Stainless steel protective rotor sleeve and stator sleeve. Four pole asynchronous motor for the BMH and DMH versions, two pole motor for the BPH and DPH versions.The single-phase circulator has been designed to work at three speeds - 230 V, while the Three-phase circulator has been designed to work at two speeds - 230 V and at three speeds - 400 V. Thermal overload protection incorporated in the single phase version.For the three-phase version the motor must be connected to the power supply through an external contactor. An automatic clapet type valve is incorporated into the delivery mouth of the twin version in order to prevent water from recirculating while the unit is not working; a blank flange is also supplied standard if one of the two motors must be serviced.