Review on Fast Low-Level Carbon Monoxide (CO) Detector for Cars, Vehicles, and Aircraft - 9ppm Alarm, Ideal for Police, Pilots, Travel, Buses, and Trucks, Compact Metal Body (2oz) by Marley Woods

was damaged. So the first thing I did when it arrived in the mail was open it, hit the power button and start the car. It finished calibrating and I checked it by going to the back of the car. It immediately began counting to a hundred, signaling, and blinking to attract attention. I went and watched it count backwards and then it stopped working. THEN I read their test instructions which said direct vehicle exhaust would ruin the sensor. I told the people at the company how I screwed up and they kindly fixed the device. I did not pay the shipping costs which I will certainly accept as a small fee for a reminder to read the F. manual. Attached image of the test as shown in their video. Use a wooden skewer and a glass. No car! The device works as described and the customer service is excellent. Thank you!