This figure compares a contour seating system installed on the surrogate and commercial wheelchair bases. The seatback canes and seat rails are similar in size and length and the hardware used to attach the seating system is the same for both bases. The angle of the seat rails is slightly steeper (or tilted rearward) on the SWCB, while the rails on the commercial base are closer to horizontal. The included angle between the seatback and seatpan are close to 90 degrees on each base.
This should be in the right column.