The testo 327-1 Flue Gas Analyser offers a robust and simple entry into flue gas analysis for domestic boilers. It measures O2 & CO and will calculate ratio, CO2, etc. The 4-line LED  display can be configured to the user's requirements, and its back-lighting function guarantees an easy-to-read display even if lighting conditions are unfavourable. The analyser stands out on account of its easy menu navigation and ergonomic housing as well as its durability. Delivery Scope testo 327 Flue Gas Analyser, rechargeable battery and calibration protocol, Flue Gas Probe (180mm x 6mm diameter), soft carry case with shoulder strap, AC power supply.