The SR-009S uses a diaphragm which consists of an ultra-thin plastic film. This film has a mass that‰Ûas close to zero and offers a high transient characteristic throughout the entire audio spectrum. The STAX SR-009S uses an evolved version of the Multilayer fixed electrode MLER (Multi-Layer-Elect-Rords) used in the SR-009. The edge of the electrode opening has been smoothened to reduce air resistance and improve sound permeability. To avoid resonance and the muddying of sound by such a thin electrode, it has been gold-plated with high specific gravity. This also gives you high speed, clarity, silky details and powerful texture. The guard mesh on the outer part of the headphone has been curved to increase sound intensity, improve resolution and lower the influence of sound reflection. The arc-shaped headband has a 10-step slider making it easier to adjust it to just about any head size.