M39 Chrome metal medium depth (around 27mm) screw mount caps for some eariler screw mount Leica Lense and others. 

Also it works on Voigtlander Lense:

• Leica 21mm f4 or similar

Works on Leica 39mm thread screw mount lens (Leica & it's copies) 

Please check my eBay Store to find more items!

Good luck and thank you for bidding.