Features "Artists Hear with This Sound" The MDR-CD900ST is a professional-grade monitor headphone jointly developed by Sony, boasting world-leading technology, and Sony Music Studios, which is well-versed in sound creation. It features sound quality that reproduces the original sound faithfully, with sharpened contours and sound images. The fact that it has been used in numerous recording studios since its release in 1989 proves its high evaluation and reliability. History Originally, the MDR-CD900ST was developed for use in CBS Sony Shinanomachi Studio (now Sony Music Studios). It was then sold as a professional-use product for studio use and has been used in numerous recording studios. It has also gained tremendous trust from studio personnel and artists, and has been featured in TV, radio, and magazines. Resolution Suitable for Monitoring By adopting a uniquely developed driver unit, the resolution (detection limit) required for monitoring has also been significantly improved. It meticulously reproduces subtle differences such as the contours of sound, positioning, and the sense of echo, conveying the "true sound" to the ears. Pure Sound Quality That Preserves the Original Sound Image Thoroughly pursuing the quality and durability required in the professional world, such as recording studios, post-production, and broadcasting stations, a uniquely developed driver unit has been adopted. This has succeeded in obtaining clear sound quality that preserves the original sound image with little distortion. Compatible with All Studio Uses By strengthening the input resistance (maximum input: 1,000mW) and the frame/cover, the sound quality is emphasized, and durability and stability that can withstand use in recording studios and broadcasting stations are realized. By pursuing various conditions from a professional standpoint, it has gained high praise and trust from studio engineers and musicians. Specifications Model Name: MDR-CD900ST Type: Closed-back dynamic Driver Unit: 40mm, dome type (CCAW adopted) Maximum Input: 1,000mW Impedance: 63Ω Sound Pressure Sensitivity: 106dB/mW Playback Frequency Band: 5～30,000Hz Cord Length: 2.5m Cord Thickness: Φ4.0mm Plug: Stereo standard plug Weight: Approximately 200g (excluding cord) It is in very good condition. I am selling it because I haven't had many opportunities to use it. Please note that returns and cancellations after purchase are not accepted.