The Model 420 has been discontinued. We recommend the ATR120 time clock or ES900 time recorder if you need a replacement. The Acroprint Model 420 is an electronic time recorder/document control stamp that handles all of your time keeping requirements. It features fast, simple, and quiet operation and can be adjusted for either weekly, bi-weekly or monthly pay periods. This unit also has a built-in signal control program to activate bells, horns or buzzers to synchronize breaks or ends of shifts. You can also get a Ni-Cad battery as a backup for full operation when AC power is out.