These batteries are a great alternative to the OEM ones. The lower price point is an obvious reason, but so far, these batteries have not triggered any warning codes on my FX30, which makes these a great choice.
I haven't noticed any big performance differences between this and my original Sony ones either. As mentioned before, I don't get any 3rd party battery warning messages popping up during the power-on cycle! And I just updated to the latest firmware on my FX30 too and so far, these batteries are working perfectly!
Overall, this is a fantastic battery set for the money. Charger works great. Everything feels quality and well-made. I also love the set includes a protective cover, one for each battery, which is great for my travels. I highly recommend it.

The K&F Concept NP-FZ100 2600mAh Battery and Charger Set comes with two 2600mAh High Capacity NP-FZ100 Batteries and a Dual-Slot LCD Charger stand. This charger stand does it right. While charging the LCD screen shows an animated battery image filling up and when it is finished it stops the animation just shows a battery image full so you can tell it it is done. Too many other chargers on the market never indicate when the batteries have a full charge. The batteries work great withe my Sony camera too. Recommended!

These batteries charge fast a last a while! I was happy to see that they didnt heat up while charging! I've had a few that has done that. The batteries lasted a long shoot that took 4hours! I was surprised! The batteries are compact and easy to travel with. They are good quality batteries.

2 batteries and charger, great value for money. I have yet to test the longevity of the batteries, but so far everything's great.

This is a REVIEW for a charger set and 2 batteries COMPATIBLE with various ranges of SONY mirrorless cameras and camcorders, sold on AMAZON with the description:
K&F Concept NP-FZ100 2X2600mAh Battery and Charger, Compatible with Sony A7iii, A7 III, A7iv, FX3, FX30, A6600, A7C, A6700, A7RIV, A7Siii, ZV-E1, ZV-E10ii, Alpha 9 II and A9S.
The fit and recognition of the charger in the camera body are perfect, at least in the Sony A7 III and A9 versions. The charger is slow but it is something that seems normal to me, since the batteries support up to 2600 mA of charge and it is a small compact double charging adapter / controller (an additional feeder is needed to supply the 5v and at least 2.5 A. of current, recommended feeder of at least 15 W. of power, either an AC converter feeder from the electrical network (220v. ~ 240 v. AC> OUT USB-A (with the supplied cable) USB-C / (Micro Usb) if it has a direct output or we have USB-C> USB-C wiring, with 5v. 3A. DC.), or a 12 ~ 24 v. DC vehicle feeder. > Output also USB-A (female base) ö USB-C wired, even in travel circumstances without the possibility of an electrical network or vehicle cigarette lighter socket we could use a large-format and powerful POWER BANK to power the Battery charging adapter. The slow charging doesn't worry me too much because, like most people, I usually leave the batteries charging overnight when I'm not using the camera and remove them from the charger in the morning. Thanks to this charger, I don't have to charge the battery through the camera or charge one and then worry about swapping it for the other afterward. I just put both in the charging bays and forget about it until the next day. It also has a separate charge indicator light for each battery.
In return for the somewhat slow charging, we have the advantage that the batteries provide very good battery life thanks to their 2600mA/h charge, providing almost 19W/h.
Considering the good performance they've been providing for some time now and the good selling price of the set, in addition to the confidence I have in this brand (K&F), which I already know and have other products from, I have decided to rate it as the highest in its category. I award:

"5 STARS" = [ * * * * * ].
I hope you find this review helpful. Happy shopping. Best regards. :*)

Perfect kit for me as my FX30 battery could only be charged when the camera was plugged in.

One of my biggest dislikes about my FX30 was that it only came with 1 battery and had no exterior charging block to charge the battery outside of the camera. It is annoying to have to have the camera body be on my desk taking up a decent amount of space just to charge a battery that would normally come with a charging block. This one from K&F comes with 2 larger mAh batteries and an external block I can setup to charge my batteries outside of the cameras body.

The batteries have a slight bit more power storage than my OE Sony provided battery which is great as batteries tend to go through juice quite fast when shooting at higher resolutions. The fact that it also comes with 2 batteries makes sure that I can have extras charged and ready to go as I shoot footage throughout my sessions.

The batteries charge fairly quickly and fit into my FX30 perfectly with no fitment issues. I would highly recommend this battery kit to those that are looking for more batteries or for those who can only charge their batteries through the cameras body.

These are great, well the whole kit.

I use a Sony A7iV and I never seem to have enough battery life left when I pick it up to use, especially for street photography.

With these extra batteries I can have them charged up and ready to go and they give me more than a full day's shooting - or extended periods of video recording.

They seem to last as long as the original and work exactly as you'd expect. Good value for money as well, compared to a Sony original.

Batteries tested in an A7 R IV, an A7 III, and an A6700.
No error messages, good charge retention, and substantial battery life.
The charger is basic but does the job well.
An excellent alternative to Sony-branded products.

I keep leaving reviews for this company because they continue to amaze me purchase after purchase. It arrives in a small box, branded K&F in white and orange as usual. Upon opening it, you'll find the charging base with LEDs indicating the charge status, the USB-A to USB-C cable, and then, well protected, the two NP-FZ100 batteries. I'm using them with my ZV E10 M2 and they work great. The option of having three batteries is very convenient. What struck me is that the two batteries have a dedicated plastic cover to protect the connections, which are certainly the most delicate part. I repeat, this brand is increasingly convincing to me.

Both batteries offer noticeably more endurance than many older replacement batteries, allowing longer photo or video trips without constant recharging. The compact charger fits easily into a camera bag and charges both cells quickly, which is particularly useful when on the go. Compatibility with common full-frame and APS-C models means that changing camera bodies does not require a new battery system. A positive aspect is that the remaining power indicator in the camera is read accurately and there are no error messages. During operation, the temperature remains unremarkable, even during burst shots or longer 4K clips, which gives confidence in the cell quality. The only thing that would be desirable is an included carrying case or protective caps to better protect the contacts in the backpack. Overall, a solid set with strong value for money for photo and video projects.