10 amp inline fuse holder like other types of fuses, the main purpose of an in-line fuse to protect the circuit of a piece of electrical or electronic equipment. If an electrical device is suddenly overcharged with current, the filament inside the fuse will melt and break the circuit. ... One of the most common uses for in-line fuses is automotive.

How to use?

To install an in-line fuse holder, you need to cut the wire (presumably in the middle), then strip back each newly-cut end @ 3/8", then cut the positive side of the sonar power cable, strip back those back @ 3/8", and connect the ends of the fuse holder to the exposed ends of the positive power cable using butt .