Combines the acoustic response of a traditional bell and diaphragm into a convenient one-sided chest piece. New gasketed diaphragm enables the scope to achieve multi-frequency response simply by altering pressure. Light pressure produces bell-type low frequency response. Firm pressure will produce diaphragm-type high frequency performance. New ovoid-shaped chest piece improves ergonomics. Chest piece made from lightweight zinc alloy plated with an attractive satin stainless finish.