A small fiberglass 2-inch Parshall Flume with a curved inlet transition and stilling well.  The curved inlet allows the flume to be directly bolted to the wall of the concrete manhole in which the flume is installed.  

Stilling wells can be used to dampen turbulence in a flume or they can be used as a convenient place in which to measure the water level in the flume or to sample the flow stream.

The flume here is used to measure treated industrial effluent from a brewery in Colorado.