The Laser BGL through-beam sensor from Balluff Inc., Florence, Ky. (, has a metal forkstyle body with prealigned optics to ensure precise and simple installation without special brackets or complex beam-alignment procedures. It uses a safe, visible, Class 2 red laser for resolution down to 0.03 mm. And accuracy is constant over the life of the sensor and over the entire length of the product being measured, regardless of sensor size. Sensors come in 30, 50, 80, and 150-mm sizes and operate on 10 to 30 Vdc. The one-piece sensors are protected against short circuit and reverse polarity, and can operate as normally closed or open.