The CPR 100A model supports manual mouth-to-mouth respiration (inhalation), simulates airway opening, and has built-in electronic detectors for compression depth and compression frequency. During the first compression, all three lights on the left shoulder will illuminate, indicating that the battery is charged, and all three indicator lights are functioning correctly. If the indicator lights do not illuminate during compression, please first ensure that the compression depth is sufficient (you will hear a clicking sound). The indicator lights will also not illuminate if you do not compress to the correct position. If the compression depth is correct but the indicator lights do not illuminate, please replace the two alkaline batteries (located inside the battery box behind the left shoulder of the simulated person). Once you start chest compressions, the yellow and green indicator lights will turn off. If the compressions are less than 80 times per minute, the red indicator light will turn on. When you increase the compression rate to 80 compressions per minute, the red indicator light will flash as an alarm. When you increase the compression rate to 100 compressions per minute, the green indicator light will illuminate, indicating that the proper compression frequency has been reached. If you slow down the compression rate, the green indicator light will go out, indicating that you need to increase the compression frequency. If your compression depth is insufficient, the red indicator light will flash as a warning display. The difference between CPR 100A and CPR 100B is that the CPR 100B does not have a built -in compressor depth and press frequency electron detector. Packing list: 1 X CPR Training model 10 X Disposable airway 1 X Black handbag