Wantek Headset for Telephone with 2.5mm Dual-Ear Noise Canceling Microphone and Volume Control, 2.5mm Headphone for Landline Phones Ideal for phone support, call centers, businesses, offices, home telephones, sales, and telecommunications. Clear calls. It's a 2.5mm pin plug. I mistakenly bought the RJ9 connector version. I confirmed receipt before realizing the mistake, so I'm selling it to get rid of it. (I opened the package, but I haven't used it.) It can only be used for telephones because it can't be plugged into a general pin plug. I plan to send only the main unit wrapped in bubble wrap, excluding the original box. (I will try to reduce shipping costs as much as possible.) Selling to dispose of it. I will switch to an auction.