Invisible variation selector number 253, a zero-width mark following a base character to choose a glyph variant, mostly for CJK ideographs.
U+E01EBVARIATION SELECTOR-252U+E01EDVARIATION SELECTOR-254U+E01EAVARIATION SELECTOR-251U+E01EEVARIATION SELECTOR-255U+E01E9VARIATION SELECTOR-250U+E01EFVARIATION SELECTOR-256U+E01E8VARIATION SELECTOR-249U+E01E7VARIATION SELECTOR-248U+E01E6VARIATION SELECTOR-247U+E01E5VARIATION SELECTOR-246U+E01E4VARIATION SELECTOR-245U+E01E3VARIATION SELECTOR-244240 characters in the Variation Selectors Supplement Unicode block, from number 237.