A flow or level switch comprises a sensor/switch assembly which is adapted for mounting in connection with either a fitting having an offset defining a channel to detect fluid flow through an orifice into the channel or a tank having a ball float to detect the level of the ball float in the tank. A switch module comprises a control rod which reciprocates and activates a switch unit having a bi-positionable contact member. A follower, which may be in the form of an axle with an angularly fixed projection, engages the control rod to cause the contact member to move.