According to :
I need to replace my water shut-off valve handle and am not sure where
to look or what to ask for. The standard plumbing supply stores seem
to stock only the square receptacle type whereas the one I have has
threads that the handle slips onto. My house is 40 years old and there
does not appear to be any name or manufacturer printed on the valve.
Thanks for your advice.

Ordinary hardware or plumbing stores can almost always help you
out, especially if you bring in the old handle.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.