That's one of the ways they're using to extend the life of an O2 sensor.
They don't even install the sensor on the exhaust pipe, but rather a remote location with an air pump that sucks some of the exhaust out to sample.
Once you pull that exhaust sample out, you can run it through an air/oil separator and over a heated O2 sensor.
It's a continuous flow system, meaning the pump is flowing exhaust over the O2 sensor at all times and nearly as fast as if it were inside the pipe.
Another benefit is that you can hook the line up to the stinger if you wanted to avoid that bit of fresh charge that gets pushed into the exhaust, preventing erroneous O2 readings.