64 Audio U18s, Audiophile Reference In-Ear Monitor, With 18 drivers and completely sound reedless design, 8 Balanced Armature woofers and 8 BA midrange drivers together with a BA midrange tweeter and the tia BA tweeter in a compact enclosure, Slightly warmer sound signature and lower sensitivity to achieve higher volume levels and meet the needs of stage and studio professionals, With 64 Audio's exclusive LID (Linear Impedance Design) technology, Modular Apex technology reduces air pressure in the ear canal for a premium, fatigue-free sound experience, Construction: Closed, Frequency response: 10 - 20000 Hz, Sensitivity: 111 dB/mW @ 1 kHz, Impedance: 10 Ohm @ 1 kHz, Crossover: Integrated 4-way passive crossover, Isolation: -20dB and -15dB by supplied Apex modules, Cable: 1.2 m (detachable) with angled 3.5 mm mini jack, Incl. transport hard case, TrueFidelity foam earpieces (S,M,L), silicone earpieces (S,M,L), m20 Apex module and m15 Apex module