Dunlop MXR M87 Bass Compressor Effects Pedal CHT Constant Headroom Technology for clear, clean performance True bypass 10 gain-reduction status LEDs Its CHT Constant Headroom Technology gives you plenty of headroom and clear performance The totally transparent M87 Bass Compressor allows your full dynamic range to shine through until your signal reaches the compression threshold, which is indicated by the ten highly visible gain-reduction status LEDs