The 30 ml bottle holds a stable

The tip traces lines that are 2 - 5 mm wide

and they trace lines that are 1 mm in width

the pen takes standard Pilot BLS-G2-7 series refills

flux industrial mop fx mop 200i flip cap NER The 30 ml bottle holdsClassic shoe polish mop filled with black FLUX FX. INK. The round tip leaves thick creamy lines, and you can squeeze the body of the marker to get even more ink out. The FLUX ink is alcohol based, so called penetrating ink that absorbs into the surface. The tip is 2 cm in diameter and it is made from foam. Best for use on smoother surfaces. The marker is refillable, and extra tips can be purchased separately.