Rule model 40 Rule-A-Matic Plus Switch without fuse holder, is compact, sleek and rugged. It has a strong, fully integrated, impact resistant cover, which protects against debris and jamming. Wires exit out on the top to keep them out of the water. Dual level anti-clog water slots. Manual testing feature allows for operations check. Use with pumps up to 20 amp. Environmentally friendly mercury-free design.