I saw these markers enough times in videos that I became curious about using one. So I found out that most graffiti shop sells these in a bunch of different sizes, from 1mm up to 40mm.
So if you are looking around for these try searching for: "empty pump marker" or "empty graffiti marker"
They allow more control for edge dying as well as reducing any fumes you might get from an open bottle.
The tips are pretty stiff which really gives great control :)
Mine are from a brand called Montana
Thanks for sharing!