Stay away from this piece of glass

Actually, I'd love to 0 (in words: zero!) Assign stars for this product. Unfortunately, that does not go with Amazon.
The only positive to vermeldende is that the eyepiece on the EOS 5D MII can be applied without any problems. That's because even on positive messages.

I bought the glasses the Extender hoping recognize the line with the recording settings in the viewfinder and better to judge the entire subject better by the reduced to 70% image. Now I see this piece of glass next to nothing. The viewfinder image is arched barrel-shaped and can not sharp face. This makes the eyepiece (at least for non-eyeglass wearers excellent) viewfinder of EOS 5D MII unusable (at least as long as it is mounted). A real letdown. What we learn from this? Next time better look. I thought it is the original of Canon. This does not reflect that. This is (an unusable) replica.