The rationale is the development of the new SR-007MK2 Earspeaker was to provide deep powerful sound previously unobtainable in-ears peakers. STAX engineers developed a unique new electrode structure. Visible through the outer case, gold plated on the outer edge this new electrode has no holes unlike conventional STAX ears peakers and thus provides an increased diaphragm vibration area allowing for rich and powerful sound yet retaining all the delicacy STAX is famous for. SPECIFICATIONS: Type: Push-Pull electrostatic circular sound element, Open-Air type enclosure Frequency Response: 6 - 41,000Hz Capacitance: 94pF (including cable) Impedance: 170k Ω (10kHz) Sensitivity: 100dB / 100V r.m.s. 1 kHz Bias Voltage: 580V DC Left & Right Channel Identification: 'L' and 'R' indicated on the cable entrance point, solid line (left) and dotted line (right) on the cable Ear Pads: Genuine Lamb Leather (direct skin contact), high-quality synthetic leather (surrounding portion) Cable: Low capacity wide format, PC-OCC (Pure Crystal Ohno Continuous Casting) 2.5m/8.2ft Ambient Temperature & Humidity: 0 to 35ºC / 90% max. without condensation Weight: 12.9oz without cable / 1.1lb with cable