The Left Black Lenticular Bracket symbol (【). Copy and paste it, or use its Unicode, HTML, and CSS codes.
More from Punctuation.
The quickest way is to copy 【 from this page and paste it anywhere. You can also insert it with its Unicode, HTML, or alt code listed above.
【 is U+3010 (decimal 12304).
Use 【 in HTML to render 【 on a web page.
On Windows you can type it with Alt+12304 (hold Alt and enter the number on the numeric keypad).
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