Cheffort Handheld Carbon Monoxide Meter, Portable Carbon Monoxide Detector, Professional-Grade CO Gas Tester with LCD Backlit Display, 0-1000PPM Range for Industrial and Home (Battery Not Included) - Amazon.com
FirePro Carbon Monoxide Alarm With LCD Display - Bunnings Australia
8 Users, 125 psi Max Pressure, CO Monitor - 4EEA3|CO91-14LAC - Grainger