Raa is about different angles of light. By turning the knob at the end of this lamp's head you shift the LED inside forth and back, consequently altering the angle of the emitted light. The acrylic shade picks this effect up. When the light cone is the most focussed it shines through the middle part of the shade. When the angle is widened the light slowly wanders into the engraved part of the shade, lighting it up and deflecting more light in the opposite direction.