[MRM]

The intoxilizer is much more accurate. It has a lot of features that the PBT doesn't have. It would take more time to explain than I have, but basically the intoxilizer draws air on its own, calibrates the air sample (0.00%) against a known solution of alcohol in the machine before having you blow in for several seconds, with a repeat. The air that you blow is tested for consistency to make sure the alcohol concentration isn't spiking or dropping, which would indicate mouth alcohol or outside air contamination. You do that twice and the machine compares the two samples for consistency. If the two samples aren't close enough, the test is not considered accurate.