These shafts are extra strong and light weight. The high density metal wires at the rear of the shaft hold your flights securely but will release the flight if it hits an obstacle already on the board. Sizes of shafts are not just for the preference of the user. Shafts come in many lengths for a purpose, and that purpose depends on how the dart is thrown. A Softer toss generally requires a longer shaft and a larger sized flight. Conversely, the harder a dart is thrown, the shorter the shaft and smaller the flight should be. When using an aluminum shaft, o-rings are strongly suggested.