In article ,
"Gary Dean" wrote:

It is basically a disk with a hole on the middle

AKA a washer.

The one drawback, as already mentioned, is the problem with inside corners.
The other problem is the lack of resolution as the 'disk/washer' will not follow
into a narrow groove, just averaging as it bridges across a narrow gap.
In most cases not an issue unless one makes it an issue as I just bloody well
did.