Now now, ladys. Lets not get all huffy. Trust me you dont want me to settle things for ya.
Spedmetal, are you sure you would want to do that to your GBA? Well because if you do you will shorten the batteries life. I know when I installed my afterburner I got less life outta my batteries.
About your question on what it is, its probably some sort of amp that pumps up your speakers volume.
I do like the blue led thingy though.
Tyler!