The Korky 528 toilet fill valve box states that the valve fits all toilets. This valve DOES NOT work properly in TOTO brand toilets. Three weeks ago I purchased and installed a 528 valve and it initially appeared to work correctly but then I realized the bowl was not filling completely. This lack of water during the initial flush subsequently caused our pipes to clog and created a plumbing problem. I have subsequently found that Korky manufactures a special valve (528T)for TOTO toilets at a substantially higher price ($26). I no longer have the packaging or receipt for the original valve so there is no possibility of returning it. I purchased a 528T today. Hopefully, it will work.