This may not hold up as well as a dedicated charger - time will tell, but so far it's another affordable and well functioning product from K&F - no battery warning in my A7r IV. Battery life at full matches with mAh indicated. So far I'm impressed.

5/5 Rating

Love this USB-C rechargeable Sony NP-FZ100 battery. This thing will help with the gear you have to take on location with you. Also eliminates option of carrying battery charger with you. Also, it charges pretty quick.

Pros
Easy to use
Eliminate need to carry separate charger with you
Charges pretty fast

Cons
None

Package comes with Battery, Battery protector, and USB-C Cable. I love the fact that I could charge this battery without bringing a dedicated charger so I can cut down on how many items I need while traveling. The battery has an indicator led on it to show when it is charging (red) and when it is charged (green). Some aftermarket batteries give various issues such as showing up as under charged (ex. 95%) or the camera will complain about the battery. I haven't had any issues and the battery seems to last just as long as the original sony batteries. And, you can purchase two of these batteries for the price of a single Sony battery. Great deal and I'll be recommending these going forward as well as picking up an extra.

Bought these batteries for the sony a7iv and fx 30 that after the latest updates give problems with non-original batteries (you don't see the percentage of charge and the battery is not compatible warning)
With this everything is ok, percentage of charge ok and no warning. .
To be tested in the field to see the actual duration.

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.

This K&F Concept battery has the same specs as the original: 7.2V, 2280 mAh, 16.4 Wh.
It can be charged on my Sony charger; I like the fact it can also be charged by just plugging in a USB-C cable and the mini-LED light signals the charge state with either green or red -- I don't get the exact level from that mini-LED though. When I connected the battery to my power bank it has drawn 10W power.
It performs subjectively very well, and I like the color feature of the battery also very much. I take several batteries with me on a shoot and being able to identify them by color helps me picking the empty or full ones easier. The cover protects the contacts and the USB-C port from dust and crumbs.

I love the new USB-C port that companies are putting on NP-FZ100 batteries. It makes it so much easier to charge up in the field with a larger battery pack, so I can alternate between two NP-FZ100s with a battery pack and be ready to go all day, rather than having pockets for charged and then discharged batteries.

Plus, I can forgo a specialized charger if I'm on a trip and want to just bring one big USB charger for all my electronics.

I just reviewed a non-name-brand 2-pack of these batteries, and they were too big for the camera's battery slot (even before any chance to heat up from use). That's scary, since it could ruin the camera trying to pry one of them out.

I didn't have that problem with this one, or with another popular trusted brand's version. They've worked fine in the field. I've been happy with products from K&F Concept, so I'm fairly confident recommending this one.

Works well. Provides credible Reharges quickly. Recharges quickly with PD charger. Since Sony does not provide a charging adaptor, these batteries become a very real alternative.

These are great for an on the go photographer. They charge well in the car. Best part is no warning on the battery in the camera.
Charge is comparable to Sony brand batteries.
I will be buying more of these.

These are a decent bunch of batteries from K&F Concept. The USB Type C charging port is a feature I welcome very much.

It has similar battery life to the OEM Sony NP-FZ100 batteries. I definitely think this is a great hit for anyone that's looking for batteries on a budget but still wants to power up their camera with confidence. I'll be using this for work, and I think it's still a great option for that.