There are two major benefits to this spool, the first is a superior axle to spool spline interface compared to an aluminum spool, the second, we are able to lose 4.5 of axle in the middle of the spool, 4.5 of nothing but air, another pound less even with our Ultra Lite axles. If you were wondering about the spiro-lox on the drive plate end of the axles in the previous picture, now you know.