Fountain Pen Ink Converter CON-40, Screw Type (CON-40)

Fits perfectly and works a treat!

I bought this to go in my Kakuno fountain pen. It fits perfectly. Would recommend

Most of my other converters can fill their pens 70-80%, this example seems to be able to fill the Kakuno pen 50%

Good so far

I had a pen I loved but couldn't use as the ink container had perished. This works perfectly and I am so pleased. My pen has a very fine nib and the ink does not run out too quickly.

Easy to use.

Very good quality, unfortunately doesn't fit a Pilot Metropolitan but returns process was prompt and hassle free

Ink capacity: The capacity of this converter is a little embarrassing. It lasts less than a week of light writing with a Pilot F nib, which is fine indeed. The whole thing is smaller than it needs to be. Not only is there a small reservoir to begin with, but the choice to put four ball bearings in it means even less ink. Which brings us to ... Ink flow: There's a bizarre choice of putting four small ball bearings in the reservoir to act as agitators to break vapour lock. While these function, it causes additional engineering problems. The first is that one agitator would be plenty. (It's ridiculous to imagine tests where engineers added additional ball bearings until four were discovered to be optimal.) More than one isn't going to acheive much (if any) more, and they take up ink room. Their small size means they might flow out Pilot's wide cartridge mouth, so flow is restricted to keep that from happening. This may be what hampered the other reviewer's ink. Looks: It looks fine. If you have a Pilot C/C pen with a translucent barrel, it could look really nice. Build quality: Extremely nice as would be expected from Pilot. Very well put together. It's just the engineering (and marketing) that's questionable.