CON-40: This converter allows you to use most Pilot fountain pens with bottled fountain pen ink, including the Kakuno. Screw-type piston filler.  Pilot CON-40 convertor holds .4ml of ink. Transparent design for easy viewing, and four tiny ball-bearings inside break surface tension for more reliable ink flow.  Clear, Diameter – Max 7.2 mm, Length 6.0 cm / 2.4 inches, Weight - Item Without Packaging 0.05 oz / 1 grams

CON-70N: This converter allows you to use fountain pens with bottled fountain pen ink. It has a large capacity and features a unique push-button mechanism. Compatible with the Kakuno, Custom 74, Falcon & Justus. Does not fit the Piolet Capless.  Pilot CON-70N convertor holds 1.1 ml of ink. Transparent design for easy viewing.  Clear, Diameter 8.7 mm, Length 8.0 cm / 3.1 inches, Weight - Item Without Packaging .15 oz / 4 grams