Systems and methods for transferring settings between user devices using gestures are provided. The protocol defines a data frame format, data fields, data field values of a group of command frames. The flexible element is arranged to move from at least a first configuration to a second configuration via bending of the flexible element. Each roll-up actuator, which has opaque characteristics, is fixed on the circumference portion of the light-transmitting region and includes a fixing end and a moving part which extends from the fixing end. Each hydrocyclone has an inlet aspect ratio, a barrel length and diameter selected based upon the mixing energy requirement determination.