SONY Dynamic Stereo Headphones MDR-CD900ST These professional closed-back monitor headphones were jointly developed with Sony Music Studios in 1989. Highly regarded for studio use in recording and broadcasting, they are still used in many professional settings today. Model Name: MDR-CD900ST Type: Closed-back dynamic Driver Unit: 40mm, dome type (CCAW adopted) Maximum Input: 1,000mW Impedance: 63Ω Sensitivity: 106dB/mW Frequency Response: 5～30,000Hz Cord Length: 2.5m Cord Thickness: Φ4.0mm Plug: Stereo standard plug *A conversion plug is required to enjoy with a portable player. Weight: Approx. 200g (excluding cord) Accessories: Case