Almost every return in this category comes from one thing: the thread was never checked. Tell us what you measured and we will tell you whether the replacement head goes on — or whether you need something else entirely.
You do not need this to send the form. But if you can do one of these three things, we can usually answer with certainty instead of a guess.
Hold the fitting against a ruler. Count the peaks in one quarter of an inch. Five peaks means 20 TPI — that is the one you want. Three or four means it is a pipe thread and this head will not go on.
A caliper across the male thread is worth the fifteen dollars they cost. Around 22.2 mm is a match. Around 21 mm is either NPT or BSPP, which is close enough to look identical and far enough not to seal.
Roll it on a flat surface. A fitting that gets visibly narrower toward the end is tapered — that is NPT, a household plumbing standard, not a commercial pre-rinse one.
Half the people who write in end up answering their own question on this page. It takes about four minutes and there is a diagram.
Read the thread and fit guide