Sennheiser open-back headphones with a 40mm driver for high-quality sound. I bought these five years ago for indoor use, but I was so busy with work that I never used them. The box is no longer available, so it's just the headphones themselves. - Brand: Sennheiser - Type: Open-back headphones - Connection type: Wired - Cable length: Approximately 2m - Driver size: 40mm Thank you for looking.