Noodler's Bad Belted Kingfisher
Originally purchased to go into my Dad's Parker 51; currently used in a TWISBI Vac Mini, fine point.
Flows well, but not a wet ink. Minimal, if any, shading. Some show-through on typical 20# bond. Works very well on security checks, with some penetration through to the other side of the check; which I regard as an asset. Pens need to be blotted after filling, or they'll initially be quite wet & prone to blob. One of my favourite inks.