A Permanent Style Palmer-Bowlus Flume with end flanges trimmed to allow insertion into an existing pipe.  

This configuraiton differs from an Insert Style in that the full width flume is provided - instead of an Insert Style where the width of the flume is narrowed to fit into a pipe.  The configuration works here because the flume is smaller in size than the pipe into which it is being inserted - again differing from an Insert Style where the flume size and pipe size are the same.