Product review (5 stars): Works Great with Other Branded Previously installed Unit
I had a Watts shutoff valve that I installed 25 years ago.  In the last year or so the valve was leaking at the spindle by the shutoff handle.  At first just a few drops then during the last 6 months enough to wet the concrete floor below about 6" in diameter.  The last straw was when I replaced the washer and once the hoses were removed I found that the cold side was not shutting off.  It produced a constant stream of drips. I now realized that several of the seals were going bad.  I had looked into a seal repair kit before, but the cost was about half of what an original replacement would be and more than the Homewerks valve here.
After reading reviews and seeing that most of these valves were 2 3/8 in on center I decided I could replace the unit by removing the large screws and placing it over my existing soldered brass adaptors from the Watts unit.
Everything worked well.  VERY IMPORTANT NOTE:  The stainless steel screws that hold the threaded adaptors on the Homewerks valve are longer than the ones on the Watts.  When trying to use these they wouldn't seat because the threaded portion on the soldered Watts adaptors weren't as deep.  I simply used the original stainless screws from the Watts valve.  I removed the O-rings from the screws on the Homewerks valve and put them on the old ones.  I also took the O-rings from the threaded brass adaptors and after removing the old ones, put them on the soldered adaptors.
With the new O-rings in place all I had to do was tighten the large screws to seat the valve and I had a brand new, non-leaking, valve.