The 660 Ultra Low Head turbine (660-ULH) is a 150mm (6in) diameter Francis turbine with a bronze runner and bronze and stainless steel guide vane and gate assembly. It uses a water lubricated rubber bearing below water and heavy duty spherical roller bearings above water to support the shaft and pulley assembly. The turbine case is fitted with an adjustable cylinder gate to turn the unit off and regulate flow.

The gate control is mounted on a heavy steel plate that includes the upper bearing mount which supports the main power shaft. This assembly is bolted to the floor or framework above the flume. The shafting is supplied to the correct length to fit site specifics. In the lowest head version, where the pit can be easily drained, this cylinder gate can be eliminated to reduce cost. The power range of the 660-ULH in an open flume is from 300 watts to 1200 watts.