Where the shape comes from
Closely tied to 西, west, the two characters sharing an early form sometimes read as a bird settling into its nest as the sun goes down in the west — the covering of dusk closing over the day. As an independent radical it is genuinely rare, now mostly a dictionary shell; compressed to 覀 it tops 要, to want, need, and 票, a ticket, ballot, contributing its shape more often than any longer story it could still explain.
汉字 filed under 襾
No published character on HSK Guide is filed under this radical yet. 汉字库.