The JetBlack Z2 Fluid Trainer is a high quality, smooth and quiet bicycle trainer that provides a more realistic ride feel than other trainers.The proprietary fluid in the JetBlack Z2 Fluid increases resistance exponentially up to 900 watts. The faster you spin the harder it gets!WHAT’S INCLUDED:– QR Skewer– JETBLACK CYCLING APPAxle Compatibility: 130mm, 135mm (QR and Boltup) 12mm x 142mm with trainer axles. Will suit most bikes with axle width 120mm and 150mmWheel Size Compatibility: 26", 27.5", 29er, 700c Some 24" bikes