3 battery replacement supply?

[Hsnopi]

Hello All,
So I got one of those Fairy Light strings. It's battery only. 3 AA. so that would be 4.5volt, right?
I ordered this: (https://www.amazon.com/gp/product/B00ZEZ0BWS/ref=oh_aui_search_asin_title?ie=UTF8&psc=1) but i read the actual reviews and i have a couple question...

1. Some of the reviews say this thing puts out up to 10v! Is this just bad quality? should I ditch it?
2. I didn't think to get the receiving end for the adapter to wire into the fairy light side. I have no idea what it is called. I mean I know the one end on the adapter is called a barrel connector but i don't know how to get or find the receiving end. This is the string of lights. (https://www.amazon.com/Homeleo-Oper...+LED+Warm+White+LED+Twinkle+Star+Fairy+Lights)

Thanks!
Jeff

 

[Audioguru]

Cheap Chinese adapters have very poor voltage regulation.
The Amazon overpriced adapter might not have a safety certification and might produce only 150mA (according to a user) then it might catch on fire if the LED string overloads it. The LED string is also from Amazon so it also does have a spec'd current.
Use the batteries it is designed to use.