Simple and accurate feedback! Select one of the four modes (compression rate, compression depth, ventilation duration, ventilation volume) by pushing indicator switch. Red light indicates improper hand placement, yellow light signals proper compression depth of 1.5-2.0 inches adult/1.0-1.5 inches child. Green light signals proper ventilation volume at 0.80 liters adult/0.50 liters child. The performance of each skill is displayed separately while averages are stored in the memory. Designed to automatically switch between the compression and ventilation modes depending on which one is being applied. For testing, simply push test start button and begin CPR sequence. Compression and ventilation waveforms are plotted in a time sequence. When stop button is pushed, averages of the four skills are shown on the LCD digital display while the printer tabulates the result on paper. Includes three rolls of paper and six “D” batteries.