Serial numbers begin around 68,000 but some prototypes are late 50,000. The 12 got several upgrades that made it worth the switch from older No. 1 and A&S models. Not only did it incorporate the No. 2’s anvil and shuttle system, but the 12 also added:

• A margin adjustment key;
• Blackened crown;
• Blackened eraser board;
• Two posts for the impression strip instead of one;
• Mesh paper tube;
• One piece paper rest which debuted with the 12 and thus a big giveaway;
• Mounted backspace key;
• Ribbon vibrator to type in two colors; and later
• The anvil lock was simplified.