The letter sets saddle width by sit bone distance; the number sets the cutout.
| Size | Saddle width | Sit bone (intertrochanteric) distance (mm) | Cutout |
|---|---|---|---|
| S1 | Narrow | Below 120 | Closed, no cutout |
| S2 | Narrow | Below 120 | Flow (smaller cutout) |
| S3 | Narrow | Below 120 | SuperFlow (widest cutout) |
| L1 | Wide | Above 120 | Closed, no cutout |
| L2 | Wide | Above 120 | Flow (smaller cutout) |
| L3 | Wide | Above 120 | SuperFlow (widest cutout) |
