What you will get:

• 1 Vaisala CO2 Probe GMP251 (A2B0C0N1), 0-20% CO2, 4...20mA New in Box Includes
  • 1 Calibration Certificate
  • 1 Quick Guide

This is my item R112 B1 S2 2659-2684.  5 were available at listing time. 

Ordering Specifications:

GMP251 A2B0CON1

• 0...20% Probe with Standard Filter
• 4...20mA Output
• Temperature Setpoint +37°C (+99°F)
• Background Gas Setpoint 19.7%O2, 93%RH
• No Cable
• No Mounting Accessories
• Single Package

Check out my other items where I have a lot of other scientific equipment and accessories for sale.

More Information:
CO2 Probe GMP251 for %-level measurements in life science incubators, cold storage facilities and all demanding applications
The Vaisala CARBOCAP® Carbon Dioxide Probe GMP251 is an intelligent, stand-alone, %-level probe for measuring CO2 in life science incubators, cold storage facilities, fruit and vegetable transportation, and in all demanding applications where stable and accurate percentage-level CO2 measurements are needed. The operating temperature range is -40 … +60 °C and the measurement range is 0 … 20%CO2.
The GMP251 is based on Vaisala’s unique,second-generation CARBOCAP® technology that enables exceptional stability. A new type of infrared (IR) light source is used instead of the traditional incandescent light bulb, which extends the lifetime of the GMP251. It has full temperature and pressure compensations of CO2 measurement – integrated temperature measurement for compensation purposes.

The sensor head is heated to prevent condensation. Digital output over RS-485: Modbus & Vaisala Industrial Protocol.
A calibration certificate is always included with the product