BP series Φ4 The world’s smallest! Ball Plunger Switches Able to provide identifying and positioning functions using notches on index rotating or sliding objects as well as output a confirmation signal. Discriminate Product Numbers BP series BP4SWA ϕ4 Mini Ball Plunger with a Built-in Switch If you need Sensor Head only, please order the product number H4A-08-02AH. See More Details! BP5MWA M5 Mini Ball Plunger with a Built-in Switch If you need Extension Cable as well as Sensor Head, please order the product number H4A-08-02A. See More Details!