The newer hand-held screening instruments are designed to sample end-exhaled breath automatically, whereas when using the older devices (Alcolmeter S-D2) the operator activates a sampling button. The choice of BBR used to calibrate the instrument is also an important factor to consider when blood and breath alcohol results are compared and contrasted. In this study a BBR of 2280 was used to calibrate the breath instruments to read directly as BAC. However, the fact that the breath analyzers read 15% low on average suggests that the BBR used for calibration should be higher.