The cable you're describing is commonly known as a "3.5mm male-to-male audio cable" or simply an "audio cable." This cable has a 3.5mm plug on both ends, allowing you to connect two audio devices with compatible ports, such as smartphones, laptops, tablets, MP3 players, or speakers. It's often used to transmit audio signals from one device to another, for instance, connecting a smartphone to a car stereo system or speakers, or connecting a computer to external speakers. These cables come in various lengths to suit different needs and are widely available in electronics stores or online retailers.