The long tails on the LED's you were looking make for more usability, just cut off what you don't need. The LED in the back if for aesthetics only, it will have no effect on the performance of the mouse so you dont have to worry about that. The orrigional optical mice used lasers to bounce light off the surface untill techs discovered that most any bright light would do, LED's are super cheap and last longer than any other light source in the price range. The optical receptor uses a red LED in most cases because RED has a lower absorption rate than any other colors besides green. And the only reason you don't see green optics is for continuity. Our first lasers were red, and so are our LED's.