Here's the product description from the time of purchase [2021]: [Bone Conduction Headphones That Don't Block Your Ears] "Bone conduction" works by vibrating the inner ear directly through the skull, delivering sound to the brain. Because it utilizes "bone conduction," which transmits sound through the bones, it doesn't block your ears. This means you won't miss the sound of approaching cars or station announcements, allowing you to use them with peace of mind while jogging, walking, or commuting. [Dual Mode] You can freely switch between Bluetooth mode and TF card mode. When doing sports like jogging, you don't need to carry your smartphone, which can be a hassle. (Note: TF card needs to be purchased separately.) [Bluetooth 5.2] The earphones are equipped with the new generation Bluetooth 5.2 version, providing a smooth experience with synchronized audio and video, without sound skipping, interruptions, or delays when watching videos, gaming, or playing music. [Excellent Fit] Bone conduction type headphones don't block your ears and are also ultra-lightweight at 32g, so you won't feel stressed even during long hours of audio or calls. [Easy Operation] All functions can be controlled with the volume up "+" button and the volume down "-" button. That's all. Please understand that this is a used item. Please refrain from purchasing if you are overly concerned about details. Thank you for viewing.