The testo 317-3 ambient CO meter provides fast and easy CO testing with a small, lightweight form factor.  An exclusive self-test mode provides worry-free operation, as it will always verify that the CO sensor is functioning, anytime and anywhere, without the need for test gas.  In addition, the self-check will ensure accurate CO measurements, without the need to “zero” out the unit in a fresh air environment.

• Three year CO sensor warranty
• Adjustable alarm threshold
• Programmable high and low alarm options
• Earphone jack, and earbuds for loud environments
• Hands free operation with belt clip soft case