Product usage device: The 2.5mm audio jack can be used in smartphones, media players, high fidelity audio devices, and many other devices, making it easy to connect external speakers or headphones. It can also be used to connect various accessories to control other functions of the device, such as a smartphone selfie stick recorder with a camera shutter release button, reverse video, and so on. 2.5mm level 4: Suitable for digital devices such as televisions, sound systems, subwoofers, home theater consoles, speakers, and speakers. Equipped with a 2.5mm level 4 female jack, it enables audio transmission through headphones and microphones