Not for A7III!

Batteries not included.

Sony's A7 cameras certainly go through batteries.

They all use the NP-FW50 batteries which are small and light - but you need to carry quite a lot of them around on a day's shoot. 

This is a simple holder for however many batteries you need!.

You can insert the batteries terminal "out" or "in" and this can provide you a signal for which are charged, which are discharged.