Product review (5 stars): Great product, If using top valve only, get new O-rings
This allowed me to replace just the top part of the valve without having to remove Sheetrock & all the work involved in getting 21 year old pipes off the old fittings (shut the main water off, removed (2) FLAT HEAD screws on top shown in picture & this allowed valve assembly to come off of brass pipe fittings).  After putting on new one, it leaked like crazy because of the 0-rings as other reviewers have mentioned (original o-rings looked fine but this valve & old one are ever so slightly different) One reviewer sanded/ground down new bottom of assembly to make work, I went to hardware store & bought new o-rings which were slight fatter but same diameter and this solved the problem, NO LEAKS.  I used #11 o-rings on the bottom & #6 o-rings on the top screws (top wasn't leaking but since I was at the hardware store anyways I thought this was cheap insurance)  I believe if I had used the entire new assembly it would have worked fine, but since I only used the valve portion it needed bigger o-rings or to remove/grind off some of the bottom of the assembly to make only 1 small groove like the original had.  For me the 0-rings were the quick easy, working solution.