As mentioned in https://github.com/Robbbb/VectorRuler/issues/10#issuecomment-922506335 A mirror vertical button to help people who are making dual-unit rulers [see here](https://github.com/Robbbb/VectorRuler/issues/5)
As mentioned in #10 (comment)
A mirror vertical button to help people who are making dual-unit rulers see here