Sescom 3.5mm TRRS Line to Mic Audio Recorder Cable with 25dB Attenuation and Headphone Monitoring Tap for Zoom H4N-PRO / H1 designed for portable digital audio recorders and mic preamps with a single output jack. The IPHONE-LN2MIC Y-Splitter cable allows you to do both monitoring and recording from a single output jack. It also features a -25dB L Pad attenuator on the Left audio channels to reduce the Prosumer Line Level output (-10dBV) to your iPhone® mic input sweet spot level. It's the perfect mating cable for Zoom H4N recorders when connecting to any TRRS 3.5mm Mic input wired for Apple standard. 18" Overall. Note: To hear the mic signal while recording, you need to use a recording software app with a monitoring feature that amplifies and drives the signal to the headphones.