I am extremely happy with this unit. I am a service tech by trade in a different industry and this is a very well thought out design. They should show the internal main circuit board, as it very nicely spaced out for easy connections and troubleshooting. The design of the circuit board lends itself to be easily repairable. The install, programming AND troubleshooting booklets are very well written and informative. Look at the information that is silk-screened on the cover plate. The existing control unit I replaced, was a THIRD the size of this unit, which is entirely way too small, to jam that much electronic controls into. If I had known swapping out my main spa control would be this easy, I would have done this sooner. You will not be disappointed with this system. There was nothing that I dis-liked about this system. Thanks to David for recommending this system.