This Review is for the PowerExtra 2 pack Replacement for Sony NP-FW50 and USB Smart Display Charger.
I purchased this for use with a Sony RX10 Mk III. Though I've not had these for long they work well and have equivalent capacity to the OEM Sony battery (see below).
There is a Caveat though that I've seen on both of the brands of NP-FW50 (the other I've tried is a Wasabi brand BTR-FW50-JWP) and that is that the Battery Meter on the RX-10 doesn't function accurately / reflect the charge state of these batteries. What I have found is that when using the Sony Battery once the meter turns orange (replace battery) you have approx. 5 minutes of run time before the camera will shut down, but with both of the aftermarket batteries there is significant power remaining... In one case a few minutes after the low battery indication came on I just set the camera on my desk and started recording 1080p video to see how long it would continue to run and was able to record over 35 minutes of video before the camera powered down. So if this might cause an issue for you the way you use your camera you might want to pick up OEM replacement batteries.. but at Two for $25 including a USB Charger compared to $50 for an OEM I'm quite happy.
A note on capacity.. I checked the charge milliamps from camera power down to full charge for both my OEM Sony battery (which was used as I purchased my RX10 and battery Used, but in great shape so I doubt it saw much use), the Wasabi and the PowerExtra batteries using the usb charger included in this package and a usb power monitor and here's what I came up with for full charge numbers:
Sony - 1973 ma Wasabi - 1845 ma Powerextra - 1832 ma
Note: I'm not saying my cheap usb power monitor is accurate and that these are accurate numbers, but the take-away is that since I used the same charger and measuring equipment the numbers do show that both the Wasabi and PowerExtra batteries do have approx. the same capacity as the OEM battery that I have.
So 4 of 5 stars only because of not accurately indicating remaining power on my RX10 M3.
I haven't tested the charger for charge times etc. compared to a Sony charger or just charging the batteries in the camera but it seems to function well enough. As for the "Smart LCD" display it's basically the typical 4 bar battery Icon that flashes with the charge state being shown by solid / non flashing segments for each of the two slots. Also- you need your own 110V to USB adapter to use this.. It does not include one.
Also I've seen some negative comments on this charger being slow and not working etc. that I want to address. I think what some people are running into is that they don't understand electrical current ratings... On the back of this charger it states "Input: USB 5V 2A (Min)" and "Output: 8.4V 800mA". Most cheap 110V USB adapters don't put out that much current (1.5A seems to be the most common), So if you plug this thing into an under-rated adapter or port you won't get the output current and might even damage you equipment if you try charging both batteries on something that is not rated for this load.
Now don't hold me to this but is appears that the 800mA output is likely for each battery channel which would make sense (0.8A + 0.8A = 1.6A @ 8.4v with a minimum input of 2A at 5V), so probably in a pinch you could use a 1.5A usb port / power hub with satisfactory results if you just charge one battery at a time.