One thing has always bugged me about the digital M series. I use vintage or non-Leica lenses, and one morning I might remember to manually set the camera to a 28mm f2 lens, but then I'd shoot all week, switching lenses multiple times, and the EXIF data of all my shots would say 28mm f2 Summicron. I know, it's not THAT big of a deal, and it doesn't affect the RAW file, but I just wanted the same features and benefits someone with a new, coded 50mm Summilux f1.4 would get. However, being cheap, I did not want to send all my lenses off at $150 a pop to get them professionally coded.
At one point I attempted to download a template from the internet, but even when printed on card stock I could not cut the small holes accurately enough to make it work.
For $75 I could supposedly code every lens I owned. I decided it was worth a shot. When it arrived I was not disappointed.
The plastic template snaps onto the M mount making it very easy to use the included marker to color in the spots that should be coded. The D-Coder gives you the best codes to use for Zeiss and Voigtlander lenses. The only downside is that it doesn't list the codes for all Leica lenses. For my 90mm Elmarit and 135mm Elmarit I had to do some googling to find the codes, but it was not hard to procure them.
I coded all seven of my lenses in about ten minutes at a cost of about $11 per lens. You can't beat that.