Er with caron
Er with caron is a letter of the Cyrillic script.
Er with caron, or often er with breve, is used in the Nivkh language, where it represents the voiceless alveolar trill, sometimes analyzed as.
It was also used in 19th-century Polish Cyrillic, corresponding to the digraph Rz, which used to have the sound value of Czech Ř ř.