Code point
U+21FF
Glyph appearance depends on your fonts.
U+21FF
SmU+21FF LEFT RIGHT OPEN-HEADED ARROW is a Unicode 16.0.0 character in the Math Symbol category. It belongs to the Arrows block.
Choose the representation you need, then copy its value.
U+21FF
8703
⇿
⇿
⇿
E2 87 BF
21FF
000021FF
%E2%87%BF
\u21FF
\u21FF
\u21FF
\21FF