It's called a smudge stick, yet once it dries, it doesn't budge. It is the softest, creamiest pencil you will ever encounter, so you should use a light hand when applying. I find that with a little practice, I can get a super fine line with this.
Though I don't wear yellow Nail Polish but Sally Hansen HD Lite is a pretty yellow that I wanted to wear. It is pretty sheer though. So I layered it on Sally Hansen Xtreme Wear Mellow Yellow. Mellow Yellow is a bit streaky polish.