Faithfully reproduces actual patient heart sounds, murmurs, and breath sounds with the advantage of instantly changing between sounds for comparisons. Stethoscopes are placed on the pliable pads of the Sounders for lifelike use in hearing the sounds. Up to 15 Sounders may be used together in chain-like fashion. LEDs on both sides of the volume control light only during systole to permit differentiation between systolic and diastolic events. This battery-operated unit is ideal for individual and classroom use and is also used during rounds for comparisons with other real patient sounds. Comes with two Sounders. Uses Plug-In Modules 1, 2, and 3. Modules sold separately.