Koss developed the KDE250 with a pair of dynamic transducers that mount at a perpendicular angle. The larger 20mm transducer is low frequency dominant and ported while the 13mm transducer focuses on mid and upper frequencies in a side firing angle, allowing greater efficiency and accuracy across the entire musical spectrum. Each features a matching set of 3 customized ear clips. Clips can be adjusted for height w/a special knurled knob on the element case assembly, dialing in comfort for a perfect fit. Koss also developed a unique hinge mechanism to allow the listener to modify the attack angle of the transducer as it enters the ear canal improving comfort, isolation and enhancing transparency.