These controls let you activate and fine-tune the cross-velocity functionality of SwarPlug. With this active, any change of velocity in a playing note (through Expression controller, for instance) is cross-faded with a different sample when it crosses a velocity range. This allows for a very realistic and dynamic playback of voices like Bansuri, Shehnai, etc...
The FADE TIME knob lets you adjust the duration of the crossfade (a second by default).