Day or Night when a fuse blows Smart Glow Fuses indicate immediately which fuse needs replacing. inchThey Glow when They Blow. inch Saves time and effort. Eliminates guesswork and testing. Makes trouble-shooting a snap, even in the dark. Built to exacting OEM specifications. Ideal for troublesome circuits where fuses often blow. Snaps into place without the use of tools. Easy identification of blown fuses in hard to reach locations. Color-coded fuses instantly let you know the right amperage of the fuse to be replaced.