The second variant,
the toothed half bush with a cutout, is
exactly what its name implies: a copy of the previous version
with part of the axle hole cut out, which makes the axle hole
larger (see Figure 4-13). This modification was introduced
to make it easier for children to take half bushes on and off
the axles, and that’s exactly what makes it much less popular
with builders: These bushes are more likely to shift when
stressed than the first variant. Other than that, it has every
quality of the original toothed half bush except that, having
been introduced a few years later, it’s newer and thus made
of stronger material.