In the case of conventional two-stroke gasoline engines for model airplanes, when the adjustment range of the oil needle is relatively small, even experienced masters cannot accurately judge the difference brought about by this small difference. But for drones that work continuously for more than 3 or 4 hours, this difference may cause a big difference in fuel consumption. Therefore, through this air-fuel ratio analyzer, the current combustion state of the engine can be displayed in real time, and this small difference can be amplified and quantified. You only need to adjust the oil needle to keep the lambda (λ) at about 0.95, and you can maintain a relatively ideal working state, which not only guarantees the service life, but also lowers the fuel consumption. Of course, due to the inherent physical characteristics of the carburetor, it is impossible to maintain the entire working range of the engine at around 0.95. That is: you adjust to 0.95 at full throttle, and maybe the lambda can only reach 0.8 (rich fuel) at medium speed. When you adjust the medium speed to 0.95, the full throttle may reach more than 1.2 (lean fuel), so this requires a trade-off, try to adjust the long-term working state of the engine to a suitable state. This is one of the reasons why the carburetor is not as good as the EFI system. When using, replace the exhaust pipe with oxygen sensor, just adjust the H oil needle at high speed, so that the lambda value on the screen is about 0.95, and adjust the lambda value at about 0.8 at idle speed, no need to worry about the engine anymore Difficult to adjust.You can use a 3S lithium battery or a 12V battery for power supply. Do not unplug the sensor when it is powered on. (Sensor only, no analyzer) Color: As Shown Material: Metal Package Contents: 2 x LSU4.9 oxygen sensor Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little differen