49mm to 82mm. The largest adapter ring is an 82 to 82 mm, into which you can also screw an 82 mm polarizing filter, as with all other sizes. The outer diameter of all adapter rings is of course even larger. 

hello,the set of rings is not fit.please check here to buy 49mm adapter ring. https://www.kentfaith.com/index.php?route=product/search&search=KF05.307 

Please note: our M42 adapter ring could not be suitable for Pentax Takumar Super Takumar Carl Zeiss M42 series（aperture pin does not fully depress, small tabs sticking out), as ours depresses the aperture pin all the way down

 

I actually have not received this adapter yet. It's shipping from China. Don't think that was disclosed in the ad. However, I do not believe this is for the Pentax Q body rather for digital and film cameras that take the Pentax K mount in its many variations. So I'm expecting to be able to mount my Leica M mount lenses on my digital and film Pentax K mount cameras, no autofocus or relay of exposure information, only to be used with manual focus and exposure. 

Hi, what's your lens size ,this square filter set with 8 adapter rings can fit lens size from 49mm to 82mm, if your lens in this range , it would be ok, thanks.