This is the factory tool from Schwinn for adjusting the clutch load on the IC and AC series bikes. It’s quite simple and VERY easy to use. Simply slip it into the adjustment ring next to the flywheel until the pin interfaces with the adjustment ring hole. Hold the tool stationary, turn the flywheel DOWN to add more load or turn the flywheel UP to decrease the load. It also comes with a bunch of replacement pins because people tend to force the tool and the pin will snap.