Logitech G502 Magnet/Battery?

Maybe metal weight? For adjusting the total weight of the mouse? Mine has some as well.

As the guy above said I think they are weights. It probably has the weight written on it, so that you can insert it in your mouse in case you want it heavier.

like they said ^ sometimes gaming mice come with weights so you can adjust the weight to the games you play

^ as the guy above the guy who's above me as the guy above that guy said

^What they said.

^one of these guys is lying

DUN DUN DUNNNNN!!! :O

I know this thread is old, but I just got a G502 mouse myself and was searching for info on it here. The piece the OP is talking about is not the weights, which are in a small plastic case and sort of a wide V-shape. aCAssassin is talking about the small battery-like disk that's attached to the plastic case that covers the mouse in the box. I think it was there to hold the front flap of the box closed. But you can take it out, put it in the case with the mouse weights, and use it to stick the weight case to a metal surface if you like. :)

It's a candy, just eat it :D