This is an NPN proximity switch. Supply voltage is 12-24 VDC.
The sensor has a Red LED "ON" indicator.
This switch is new old stock. Includes mounting screw.
Actual picture of switch - with 90 day Warranty      
For additional specifications see:      
http://www.acecontrols.com/PDF/StopLight_14.pdf      
For other sensor needs see:      
http://www.kkdepot.com/category.asp?cat=37      
Price $40.00 each (2 available)