Ultra Fire 10440 3.6V 500mAh
I use this battery for Janty Stick?
Now that's a good question that I don't feel entirely qualified to answer, but here goes....
My response would be no, don't use them in the Janty Stick.
Be careful of certain branded
batteries - they can be over-sized and may not fit.
How will a higher mAh possibly affect the circuit board? (Electricians/battery experts out there?)
But also you will invalidate the warranty if you use any other battery than the one that is specified for the Janty Stick.