Belonging to the fountain pen 146 (Le Grand) is the ballpoint 161 Le Grand with about 148 mm length; the 164, on the other hand, is made exclusively in the smaller size of around 136 mm. If one encounters a writing instrument with 148 mm length and 15 mm diameter that bears "164" and shows "Pix" on the middle ring, it is in fact a 161 Le Grand. "Pix" is a registered trademark of Montblanc and a compulsory feature for originals; a "converter" is a refillable ink cartridge. A model overview can be found on fountainpen.de.