20A 250V glass fuse is a fast-acting glass barrel fuse. It is an electrical safety device that provides overcurrent protection to a circuit. Its basic ingredient is zinc wire or strip, which melts when too much current flows through it. The fuse has a cylindrical shape with contacts on each end. Contact points are made of high-quality metal alloys for better performance. It is made for circuits operating below 250V at 20A. Since the glass case is transparent, you can easily determine if the fuse is blown. It is easy to install and replace the fuse.