Info from Manufacturer: The Quantum HM3, High impedance Microphone cables are designed for use with high impedance microphones requiring 3 pin XLR connections at the microphone. Standard wiring configurations are pin 3 hot (tip) and pins 1 and 2 negative (tied to sleeve), the wiring scheme for the majority of high impedance mics from companies such as Shure Brothers. All Quantum HM series cables utilize our Q-2000 single conductor audio cable and Amphenol XLR and G & H 1?4? connectors. The model number is formed by HM3-+ length. For example: HM3-25.