This type of battery test is widely available under different names. I bought on two factors : (1) price, and (2) it's a moving needle type, which attempts to indicate power left rather than simple voltage. An example of why this is important:
I have another battery tester which uses a digital display and has a button cell. It wasn't working. I tested the button cell with a multimeter and got a satisfactory voltage reading. I concluded the tester was a dud and bought this one.
On getting the new battery tester I tested the button cell. It was actually flat, despite the multimeter saying it was OK. Oh well, now I have two battery testers.
For the price the Haobase Battery Tester is a great item. I recommend it.