T9 in-ear monitors, Knowles double-armature balanced transducers, hand-assembled, all-system compatible 3.5 mm stereo mini jack plug, sturdy, replaceable 120 cm cable, ideal complement to the U4 system, 3 sizes of ear tips, case, cleaning tool, 6.35 mm, frequency response: 20-16500 Hz, impedance: 59 ohms, sensitivity: 120 dB, weight with cable: 18.6 g