A thinned G-Pen, that allows for better control over line-width. It looks best if you change your brush tip to a crosshair.
Should work right out of the box :)
If you want to hide the size circle around the brush
File -> Preferences -> Cursor
Change pen-type cursor to Sight.
If you want to hide the size circle around the brush
File -> Preferences -> Cursor
Change pen-type cursor to Sight.