Overall strength is enhanced by using polycarbonate resin. It's now easier to tell between locked and spinning... Spinning shafts have a rounded top and Locked shafts have a flat top. Also, the top of the locked shaft is now in a matte finish.If you install flights onto a Locked style shaft and then onto a Spin style shaft, you may notice the flight is looser than normal and may pop off easier. Avoid this by using separate flights for Locked and Spin shafts.Details: