16 characters in the Supplemental Arrows-A Unicode block.
U+27F0UPWARDS QUADRUPLE ARROWU+27F1DOWNWARDS QUADRUPLE ARROWU+27F2ANTICLOCKWISE GAPPED CIRCLE ARROWU+27F3CLOCKWISE GAPPED CIRCLE ARROWU+27F4RIGHT ARROW WITH CIRCLED PLUSU+27F5LONG LEFTWARDS ARROWU+27F6LONG RIGHTWARDS ARROWU+27F7LONG LEFT RIGHT ARROWU+27F8LONG LEFTWARDS DOUBLE ARROWU+27F9LONG RIGHTWARDS DOUBLE ARROWU+27FALONG LEFT RIGHT DOUBLE ARROWU+27FBLONG LEFTWARDS ARROW FROM BARU+27FCLONG RIGHTWARDS ARROW FROM BARU+27FDLONG LEFTWARDS DOUBLE ARROW FROM BARU+27FELONG RIGHTWARDS DOUBLE ARROW FROM BARU+27FFLONG RIGHTWARDS SQUIGGLE ARROW