Feature●√Photoelectric Switch Tester YH-800.●√Proximity Switch Magnetic Switch Testing Instrument Sensor.●√PNP mode output yellow light on, NPN mode output yellow light on.●√The green light is on when the switch is connected, and the red light is on when the battery is low.●√Standard of Quality: Every photoelectric switch tester YH-800 undergoes a variety of stringent tests before it leaves the assembly line.Theres nothing more important to us than you! Any question please feel free to contact us.Description