After the Extreme design of V4.0, a toned down version was created.
V5.0 also implemented a small roll stop.
The roll stop material was natural stone material called calcedony.
It did work quite well.
however, it rather looked odd.
also, i couldn't guarantee the stone will stay there for decades of use.
it was later removed, as i feared it would fall out on its own eventually, even if a strong adhesive was used.
