The Shure In-Line Hi-Pass Filter rolls off low-audio frequencies to reduce 60 Hz electrical hum and low-frequency-wind-, air-conditioner-, stand-, and floor-transmitted low-frequency vibrations.

When loaded with a low-impedance microphone input (800 ohms or more), the roll-off is 12 dB per octave below 100 Hz. When loaded with 150 ohms, the roll-off is 3 dB at 100 Hz. The output is flat above the roll-off point (with a maximum loss of 0.5 dB at 1 kHz).