By combining state of the art suspension damping technology (Inertia Active System) with dual air chambers, Progressive Suspension has created the ultimate rear suspension. The Airtail IAS is the result of years of R&D and represents the pinnacle of high performance and tunable suspension. Utilizing both a coil and air shock allows the Airtail IAS to ride like traditional high-end shocks while still allowing for extensive height and spring rate tuning. The dual air chambers permit the rider to adjust ride height INDEPENDENT of suspension firmness. This translates to the ideal ride height, without any sort of compromise in ride quality. Also available with on-board compressor and Control Center allowing for on-the-fly tuning.