The Sennheiser IE 900 in-ear headphones feature precision-manufactured aluminum housing to faithfully protect the dynamic TrueResponse transducers, found at the core of Sennheiser s innovative X3R technology. High-fidelity recordings are pieces of art and should be heard in every detail, the IE 900 displays the full potential of every recording. If it s a masterpiece, you ll hear it with impressive, sparkling trebleand no trace of sibilance. Powerful lows free from muddy mids and the ability to resolve fine detail, alongside warmth and comfort for extended sessions. All these qualities come from inspired feats of engineering. For example, Sennheiser s trusted 7 mm transducer has made it just that much better for the IE 900. All-new X3R triple-chamber absorber is also technology milled right into the solid aluminum core with its downstream acoustic vortex. Together, these innovations offer a unique level of balance and transparency without compromise.