Review on Foto&Tech Wireless IR Remote Control for Sony A7R IV III II, A7III A9 A7 II A7 A7R A7S A6600 A6500 A6400 A6300 A6000 A65 A77 A99 A900 A700 A580 NEX-7 NEX-6 NEX5T - Video Photo Modes (2 Pieces) by Drew Poulin

Now I have four of these remote releases, all Foto&Tech. They look the same, but they aren't. And there is no indication that they are different versions. The difference lies in the battery holder and locking mechanism. console stop lever on a holder straight; the rest oblique. The problem is that locking mechanisms are not interchangeable with controllers. The second problem is more serious. Some CR2025 batteries work with controllers and some don't. I've tried several new batteries from different manufacturers, checked everything for the correct voltage with my VOM meter. Panasonics and an unnamed battery brand didn't work on any of the four controllers (i.e. the problem isn't the faulty controller)! I have no idea why. My advice: take a fresh spare battery with you, but check it for compatibility beforehand.