i have this mouse and it's a good one and $20 is a good price.

the description lacks mention of a neoprene pouch (with velcro flap) which i like better than my logitech v470's nylon purse (string-drawn) as it feels like it provides better protection in a laptop bag/backpack.

i like the v470's functionality better (has a tilting scroll wheel), but i like the feel of this mouse better (rubbery texture compared to the glossy slick plastic of the v470). this mouse does have a 4th button on the left side of the mouse, but not advantageous to me as i'm left handed (ie it's not easy to push the button with my pinky).

and even if the associated laptop/computer doesn't have built-in bluetooth (neither my laptop or netbook do), you can still use a cheap ($1) bluetooth dongle (they always work well under linux) and not have to worry about losing or breaking a proprietary dongle like all the other wireless mice. but why do bluetooth peripherals cost so much more (as they don't even include a dongle)?