when Sony updated the firmware for the A6700 last year, apart from fixing some bugs, they 'discouraged' the user from making use of 3rd party batteries, with the rather alarming message above. (I gather the same message appeared in other recent Sony cameras after updates) with this message appearing with batteries that were behaving normally prior to the update. They can still be used, but with the battery life percentage display removed, and the message recurring each time the camera was switched on.

Although K & F Concept have not listed the A6700 as compatible, it certainly is, and it is "goodbye!" to the 'error' message above.

An immediate advantage over the OEM battery is the inclusion of a USB C port for charging (possibly to update the battery firmware in the future if needed?) and a cover plate to protect the battery contacts and USB socket when not in use.

In my own test, the battery life of the K & F Concept battery at least matched the original - I cannot comment on the longevity of the battery (it is new) but, having several other products from K & F Concept, suspect that the quality of their battery is going to be very similar to Sony's.

If the battery fails in what I consider to be 'early', I'll come back to the review and correct my opinions.