Lanzar vibe211 Owner's Manual page 3

Input Level Controls -
Enables the matching of input levels to the
output levels from the head unit (or other
signal source).
High Pass Filter -
When Crossover Mode Selector is in High Pass Mode,
this control limits the frequencies which will be
distributed to the speakers to those above the value to
which this is set within the range 40HZ-3 kHz.
Crossover Mode Selector -
Determines the mode of built-in crossover:
low pass (permits only low frequency signals to
pass to speakers), high pass (permits only high
frequency signals to pass to speakers), or flat.