The LC100 is an all metal 4 port 3.5mm stereo compatible listening center. It is an intentionally SIMPLE device and intentionally ROBUST to provide the longest troublefree service life and therefore highest value to schools. (Afterall, our taxes pay for them, right?). The LC100 is small enough to adhere directly to any classroom audio device thereby converting many low cost consumer electronic products into viable classroom equipment. When the equipment wears out, simply remove the LC100 and move it to another product. NOTE: The LC100 is shielded and therefore may act as a passive mic combiner when used with (preferably matched) microphones of sufficiently high impedance. All plugs must be configured according to the same wiring convention for this to work.