Koso North America Air Fuel Ratio Gauge - 2/4-Stroke - Wide-band BA004068This back lighted wide band air fuel ratio gauge will give you information on your engine to allow a more precise tuning. The programmable warning will tell you if your engine is running too lean or too rich. It is easy to install on either 2 or 4 stroke engines. Includes gauge, mounting hardware, O2 sensor and weld in sensor mount Must purchase 2 stroke sensor adapter separately, P N 27 5721