The Poslaju package that reach my house:
It comes with 2 Duracell AAA battery:
Compare to my previous mouse, the size is smaller : ( not very suite my big hand.
Overall the bluetooth mouse is quite nice, easy to pair, and once paired, everything is automatic. You can turn off the mouse anytime, and once you turn it on, it automatically connected to your PC/Laptop. I choose bluetooth over normal wireless mouse (with a USB receiver) because it doesn't use my limited USB port. So, switching from the old wired mouse to this bluetooth mouse, I get extra one USB port. My only complain for the mouse is the size of the mouse (too small for my hand).