Koso Air Fuel Meter Honda Grom Koso has over 30 years of experience in designing and manufacturing high quality products. They are known for their product's quality, reliability and capability. This air/fuel ratio meter is specifically designed to help tune your carbureted or fuel injected engine. Compatible for 4 stroke engines only. Features Properly tune the engine and help you avoid engine problems Simply connect the meter to the 12Vdc power source and plug it to the oxygen sensor and you are ready to go Display range is 12.2-17.2 If the A/F ratio is higher than 17.2, the display will show -L- If the A/F ratio is lower than 12.2, the display will show -A- Meter size: 2.36 W x 1.18 L x .45 H