⇄
RIGHTWARDS ARROW OVER LEFTWARDS ARROW
U+21C4
⇅
UPWARDS ARROW LEFTWARDS OF DOWNWARDS ARROW
U+21C5
⇆
LEFTWARDS ARROW OVER RIGHTWARDS ARROW
U+21C6
⇇
LEFTWARDS PAIRED ARROWS
U+21C7
⇈
UPWARDS PAIRED ARROWS
U+21C8
⇉
RIGHTWARDS PAIRED ARROWS
U+21C9
⇊
DOWNWARDS PAIRED ARROWS
U+21CA
⇋
LEFTWARDS HARPOON OVER RIGHTWARDS HARPOON
U+21CB
⇌
RIGHTWARDS HARPOON OVER LEFTWARDS HARPOON
U+21CC