SICK hazardous area proximity sensor model PLS101-312, part number 1016066. 
One unit remaining - discounted because original box and manual are missing - see photos. Unit appears new - original seals are still in place over power input and interface ports. To view a full technical description / datasheet (PDF), 
click here. To view a short summary of specifications (PDF), 
click here. Software is available on the manufacturer's web site.