These labels are not only extremely handy, BUT they also glow in the dark!  Can be placed anywhere on your harmonica or TurboLid as long as the surface is free of any residue.  Just cut the key you need, peel off the backing and apply.  When exposed to a light source for around 10 minutes the glow effect should last around 6 hours or more.  These stickers will be very helpful for those who play gigs and need to see their harp in less than ideal lighting.