I've got a couple of valves that look a lot like these:

https://images-na.ssl-images-amazon....ML._SY355_.jpg

(They fell out of the plumber's van so I do not have a make)

Anyone know where I can get non turny caps for those? This rad is
supposed to stay on as a shunt (though we do have an auto bypass as well
so not going to blow up)

The valve stem ends in a square rather than a rectangle. Just need nice
chrome caps that don't allow the valve to be operated - they're too easy
to knock right now.