I have a 50mm summilux v1 and it uses the 43mm filters......I also use the proper hood 12586...I own a Leitz 43mm green filter that I bought on ebay and have used it once in 8 years (I don't use green filters)......it is the easiest to use because the hood can be clipped on and off without removing the filter....that said, I have a 43mm uv and a 43mm medium yellow ,both are B+W...they are not as easy as the Leitz....I have to place the filter inside the hood and squeeze the little silver buttons on the side of the hood (little metal teeth retract) and the filter rests on the lip inside the hood...then I place the hood on my lens and once again, squeeze the silver buttons on the hood (the little metal teeth inside the lens hood retract, there are actually two rows of metal teeth, one row grabs the lens and the other grabs the filter ) and it allows me to place the hood on my lens...then I have to hold the edges of the filter (without trying to get finger prints on my filter) and screw the filter onto the lens...once on it is pretty secure, in the sense that the lens hood is actually being "sandwiched" by the filter and the lens.....wow, this all sounds rather complicated but in reality, it is not a big deal....I only have one 50mm and I usually shoot black and white, I don't hesitate at all if I want to shoot a roll of color mid-roll through a B&W roll, I will switch out the film for a color roll and quickly change filters going through the process above rather easily....that said, if I could find 43mm Leica uv and 43mm medium yellow filters , I would buy them......as far as the quality of the hood is concerned, I have had the thing actually not work before....somehow the springs ( I think they are flat, thin shim springs) inside the hood were not lined up properely and I couldn't get the freaking hood off the lens.....I could not get the metal teeth to retract and take the hood off so I could switch filters.......it only happened to me once and it was on the streets of Calcutta, it was super annoying.....but whatever....I am not impressed with the lens hoods on any of my Leica lenses.....I prefer the Zeiss bayonet mount on my Hasselblad any day.....well, good luck whatever you get..the lens itself is excellent (at least for me it is)........cheers...Michael