The Concept 2 Model D indoor rower has a lever on the flywheel housing. The lever settings 1–10 indicates the damper levels. Damper setting is NOT the same as resistance setting.
A flywheel is spinning inside the housing and the lever controls how much air is let into the housing on each stroke. More air slows the flywheel down faster on the recovery, requiring more work to accelerate it on the next stroke. The air friction builds up when the flywheel spins faster. The perceived resistance in the handle is controlled by your rowing intensity which means how hard / fast you pull.
The damper settings is more like a bicycle gearing that affects how your rowing feels. A higher setting feels like a big slow rowing boat. A lower setting feels like you are rowing a fast racing boat. A damper setting between 3–5 is recommended for most workouts. A too high setting may cause risk of injuries on your lower back.
Vary your damper setting to achieve different types of workouts. In general, lower damper settings are best for aerobic workouts, while higher damper settings make rowing more of a strength workout.
Damper setting is also called Drag Factor and the PM5 performance monitor measures this rate of deceleration of the flywheel. The measurements are self-calibrated so the monitor can read out the accurate numbers for the Drag Factor. See how to use the PM5 performance monitor.