ALERT J4X is a handheld pre-arrest breath alcohol-testing instrument that reliably identifies alcohol-impaired drivers. It's full-featured design provides officers with objective, unbiased results with easy one-button operation. To use, just breathe into the unit for 5 seconds. The unit monitors the breath flow to ensure an accurate breath test. If the subject should abort the test, ALERT J4X is ready within 45 seconds for a retest. Results are displayed in a few seconds with an accuracy of +/- .005 percent, the standard for evidentiary testing. ALERT J4X's electronic sensor operates in inclement weather, hot or cold, without a loss in sensitivity or accuracy.