We’ve received many requests from customers to put our Air Flow Highback with Ride-Stride on the SL chassis. We now have a few of these built up and stocked in our store. The Carbon SL comes with our carbon fiber highack and the SL (Dupont Zytel Highback) comes with the Air Flow Highback with Ride-Stride. Retail price on the SL (Dupont Zytel Highback) is $749.99.