Accessories ✅ Included: □ 3.5mm adapter □ Cable: 6.3mm stereo standard plug (unbalanced) □ Cable: 4.4mm plug (balanced) □ Purchased storage case ❌ Missing: □ Original pouch □ Outer box Product Condition Purchase date: Approximately 1 year ago Usage frequency: Low (rarely used) Storage condition: Stored in a separately purchased storage case Smoking environment: None (non-smoker) Pets: None (no pets) Notes: The main unit and cables are complete and function without any problems. Only the box and pouch are missing. Product Description Sennheiser's high-end headphones, which lead the world's audio scene beyond the times with their well-balanced and natural reproduction. Features of the HD 660S2: Delicate sound reproduction Rich low-frequency expression Perfectly balances conflicting technical requirements Provides a unique and dramatic sound experience, from familiar songs you've listened to for years to songs you're hearing for the first time Manufacturer's official website: https://jp.sennheiser-hearing.com/products/hd-660s2