The Autopen Model 400S was a mechanical signature machine featuring an electronic paper feed. Just like other Autopen models, the machine can use any type of writing instrument. This time saving device was most often used for general business and public service purposes, especially where higher volumes of signature reproduction were needed.
The paper feed mechanism on the 400S is controlled electronically. The 400S featured an LCD display and button control.
Modern paper-fed signature machines feature a greatly expanded capacity and a more reliable feed mechanism, enabling a higher number of signatures to be duplicated without operator intervention.