My favourite pen, the Kuretake no.50 fountain brush pen installed with a no.13 brush (synthetic) with a platinum carbon ink cartridge. I use this to draw all of my preliminary artwork for
Kuretake No. 13 Fountain Brush Pen - Black Body | JetPens
Amazon.com : Kuretake MANNEN MOUHITSU Fountain Brush Pen (No.13), Great for Inktober, Black Body with 3 Spare Cartridge, Flexible Brush Tip for lettering, calligraphy, illustration, art, drawing, Made in Japan : Arts, Crafts & Sewing