The product worked well for four months.  A week ago the hot water side gave a tiny stream on each of the three "settings."  The cold water side worked well, except the third position gave exactly the same stream of water that the second position gave - for both hot and cold.  Then the flow returned for both hot and cold, but with no increase in flow for the third position.  I called the plumbing company that sold and installed it to explain the issue.  Two plumbers from the same company came today but claimed it is working properly, and that the third position does not increase flow - it is merely a convenience feature. Since I have no paperwork (the original plumbers from that company kept it), it seems there is noting I can do.  Live and learn!