I have a 40mm C T * and to date have not found a reasonably priced UV filter as yet. Took me 2 years to find a front lens cap at a decent price and only a year to find the lens shade.
Only I problem I have is you can only use one, a filter or a lens shade. So it is the only lens I have without a uv filter much less a 6 stop ND. Love to find one myself. Bay 104 is it, I think?