THE BEST INVESTMENT YOU COULD EVER MAKE... Protect yourself from driving drunk and ruining your or someone else's life. Know your limit... Quick and accurate test results with a simple one-button operation Electronic airflow sensor to ensure a deep lung sample for testing 0.000 - 0.400% BAC (blood alcohol concentration) Semicoductor sensor with 4 digit display for upgraded accuracy 9V battery or DC cord power options Includes 9V battery, mesh carrying case and 5 mouth pieces