In truth, it's old technology but quite good technology if you are not interested in exceeding the limits.
I had one for a long time and it took some beatings; one evening it was permanently firing in my pocket when I didn't know...all the way to totally drained.
For the money, they are not a good deal anymore, not really. Mine was finally killed by leaving a leaking evod clearomizer on it for 24 hours.
It did last longer than all my Spinner batteries, but ultimately, it wasn't really powerful enough for
tanks
like BVC and other dual coil tanks, so personally I wouldn't recommend it, no.
It's probably over $25, even from China, and you could buy something in a small box form that is better in every respect and cheaper.
If it interests you, when Kanger changed their small clearomizers (evods, mini Protanks etc.) I was sent some clearos like the evod 2 and evod glass and protank 3 by a UK vendor to offer a review.
I tried them out on a genuine mod (variable volt) and the iTaste vv4 and the Vision Spinners.
My conclusion was that the iTaste VV v4 was not powerful enough to use dual coil clearomizers satisfactorily, so I refused to review the products, because calling them "good" when they needed to be used on a proper mod would be misleading new vapers.
So - this battery might make you happy with evod 1 or Protank mini 1&2, but not with anything more power hungry.....
it also won't bring your K1 atomizers to life, sadly.
The CLK was more powerful, by the way, and curiously cheaper.