Pilot CON-40 Fountain Pen Twist Converter
The CON-40 fits all of Pilot's current fountain pens, including the popular Metropolitan and Kakuno. Holds approximately 0.6 ml of ink.
I bought it for my Pilot Metropolitan. It appeared this converter carries less ink than the squeeze converter the pen comes with. I don't think it was worth purchasing this converter.
However, my order was on time and there was a pleasant hand-written "Thank you!" message on my receipt.