Two stars is the result of five stars for function after installation, but one star for manufacture. The wires are connected to the back in a way that makes them break off easily during installation, without being able to simply replace the broken wire. Only option then is to buy another. That just happened to me which made the net cost very high.
(Updated Customer Review: "I recently wrote a not-so-good review of the metal inlet valves because of the manner in which the wires are connected on the back, and the fact that there does not seem to be a way to readily replace a simple broken wire. Without my having requested anything, upon reading my review the company immediately advised that they were refunding the cost in full. That's extraordinary customer service.")