About 14 years ago I had these Seymour Duncan active P-style pickups installed in my bass. They have 3 little switches ON the bottom pickup, and I think they sound great! I was basically a kid when I first got them, and I never did get any kind of instructions with them. I've always pretty much left the switches at one setting that I thought sounded best. Now I'm wondering a couple things: -What does each switch do, exactly? Does it just boost certain frequencies? I know one setting seems to give a brighter sound, but after that it's hard to tell. -Can they be switched "off" to passive? I never tried them without a battery. I don't think Seymour Duncan makes 'em any more.