Littelfuse MS Series external mount Microswitches offer permanent blown fuse indication to PSR Series High-Speed Square-Body Semiconductor Fuses. They have one normally open (N.O.) and one normally closed (N.C.) contact rated for 4A, 250Vac. These microswitches have a visual red flap or arm indicator that releases after fuse blown condition and can also be used for resetting the microswitch contacts.