Efector     IFA 2002-FRKG/IF 5598    inductive proximity sensor

Sensor is 3-3/16" long

• Sensing Range: 2 mm 
• Operating Voltage: 10–55 V DC

According to Gemini...
• Output Function: Selectable/Programmable Normally Open (NO) or Normally Closed (NC), compatible with PNP and NPN two-wire DC technology
• Switching Frequency: 1,100 Hz
• Housing Dimensions: M12 x 1 thread, length 83 mm (flush mountable)
• Body Material: Plated brass housing with PC sensing face (or stainless options depending on sub-series)
• Protection Rating: IP67
• Operating Temperature: -25°C to +80°C

Made in West Germany