Some articles on rekelech:

... (Yiddish רעקל) or Lang Rekel (plural rekelech) is a type of coat worn mainly by Hasidic Jewish men during the Jewish work-week (Sunday-Friday) ... Rekelech are generally made of a black or navy wool blend or of worsted wool ... Many Hasidim in the past did not wear wool clothing, and the new polyester rekelech actually make it easier to keep this old custom ...