The Pilot CON-40 Converter lets you use bottled fountain pen ink with compatible Pilot fountain pens — including the Metropolitan, Kakuno, Explorer, Prera and Capless. A simple, reliable twist-type converter at an accessible price. How it works: Twist the knob at the base to expand the reservoir, submerge the nib in your ink bottle, then twist back to draw ink up. Ink capacity is 0.4ml — enough for extended writing sessions. The agitator bead inside the reservoir keeps ink circulating and prevents it pooling away from the feed, helping maintain a consistent ink flow even as the ink level drops. Compatible with: Most Pilot fountain pens using the proprietary Pilot cartridge fitting, including the Metropolitan, Kakuno, Explorer, Prera, Custom 74, Custom 912, Prera, and Capless/Vanishing Point. Specifications: Type: Twist-type piston converter Ink capacity: 0.4 ml Compatible: Pilot fountain pens (proprietary fitting) Brand: Pilot If you're new to using bottled ink, the CON-40 is the easiest way to start. Pair it with any Pilot Iroshizuku bottled ink for a beautifully curated writing setup.