Each earpiece contains two separate speaker units, precisely engineered to provide the widest frequency yet maintains a high sensitivity of 108dB. Speaker units feature PEN diaphragms 12 microns thick, CCAW voice coil and Samarium Cobalt magnets. Overlapping double drive construction with 30mm tweeters (fore), 50mm woofers (rear). High grade linear crystallised Oxygen free copper leads. Gold plated jack plug.