In the words of Red Panda:

The Radius is a ring modulator and frequency shifter with pitch tracking and an advanced LFO. It is designed around a novel “eight-quadrant multiplier” algorithm that smoothly transitions from ring modulation to frequency shifting and allows different frequency ratios for the upper and lower tones. Radius puts complex harmonic structures, bell-like tones, metallic textures, frequency shifting, soft tremolo, and bubbly phaser sounds at your fingertips.