What does OSS exhaust system mean?

The OSS exhaust system is identical in size and appearance to the standard exhaust system. The only difference is that the Oxygen Sensor Screw was welded into the elbow pipe instead of the cylinder head.
Thus, the much cheaper carbureted cylinder heads can also be used for injector engines.

Item code exhaust OSS: Surcharge for all types of exhaust systems Price: + 14 USD

The newer type of CBR 125R and CB 125R with cbr engine also has the oxygen sensor in the elbow tube.