This part is a kind of semiconductor called APM-D3B1-S.
Function of this product has Compact Proximity Sensors.
Manufacturers : Yamatake
Image and pinout :
Some of the text within the PDF file :
6 Specifications APM Series FEATURES Compact Proximity Sensors Compact Proximity Sensors Can be Installed Anywhere. Locking Boss Ensures Easy Mounting. This thin 5.9mm (side sensing type) sensor takes up little space. 8mm wide, compact with a 2.5mm sensing range. Locking boss allows easy mounting by single screw. Mounting bracket not required. (locking boss type) • Indicator lamp visible from all three directions allows easy checking of the operating state. • Wide variety of sensor types support all kinds of applications. • • • click ORDER GUIDE • DC 3-wire type Appearance Sensor package style Top sensing type Dimensions (mm) W D H 8 D H Not provided PNP Top NPN Provided PNP Side sensing type 2.5 Not provided PNP 8 25 5.9 Side NPN Provided PNP Side s [ ... ]