Although in the text it's just described as "a Chinese box" with a 5000MaH battery and the ability to record to its 32Gb of space in chunks of 30 minutes, as MP3 taking about 28mb each.
That section goes on to describe trying different microphone positions, as it makes a great difference to quality. OP originally tried it in a bag but the results were medicore, so moved to a different configuration which, although less comfortable, produced superior audio results.
the particular choice was for the battery and the other for the size, both are generic and come with the same software and bios, several vendors, if I could buy something better I would look for one that can have a lavalier microphone
I bought two, both from Aliexpress, no brand both, the one on the picture has a 5000 mAh battery, bulky but last a lot, and the other one is tiny but with short battery life, a lot of sellers on Ali, I pay around 30$ for each, both have the same software and bios, only difference is the size and battery.
