Not sure if this is the best place for this but I couldn't find a better one. I went to the Fotodiox site the other day for some reason and while wondering around I found that they have auto extension tubes for E mount. The set, 10 and 16mm, was just under $50 so I ordered a set. (They also have them for other mounts.) They came in the mail today. They are plastic, including the male and female bayonets. They work on my A7R without a hitch. Stacked as well as individually. I did a quick test with 24-70. I would not consider them heavy duty. But for an occasional shot needing close focus they should be fine.