I am just learning how to use it but am excited to see what I can create.

This is a great brush.

Does anyone know the actual mm length to each line brush?

I actually use this for painting and it gives perfectly defined straight lines.

I bought one of each of Orlys brushes and love them all! Would definitely encourage nail artists to give these brushes a try. Granted they are a little bit more expensive than the ones you can pick up from the overseas online stores that take months to arrive. But these brushes are total quality. Fine details are so much easier now. They are weighted properly and feel great in the hand. Definitely 2 thumbs up!