TALLIT KATAN (Heb. טַלִּית קָטָן; "small *tallit"; Yid. tales koten, arba kanfot, or arba kanfes; and tsidekel, from the Ger. Leibzudeckel), a rectangular garment of white cotton, linen, or wool with ẓiẓiyyot ("fringes") on its four corners. Whereas the ordinary tallit is worn only at the morning service, strictly observant Jews wear the tallit katan under their upper garment the whole day, so as constantly to fulfill the biblical commandment of *ẓiẓit (Num. 15:39), a reminder to observe all the comandments of the Torah. The tallit katan is, therefore, often worn in a manner that it may be seen; if not, that at least the ẓiẓiyyot hang freely and are visible (Sh. Ar., oḤ 8:11). The minimum size of a tallit katan ought to be ¾ ell long and ½ ell wide (15 in. × 10 in.). According to another opinion, it should be one square ell (20 in. × 20 in.). The tallit katan is put on in the morning, and the following benediction is said: "Blessed art Thou, O Lord our God, King of the universe, Who hast sanctified us by Thy commandments and commanded us [to wear] the ẓiẓit." The tallit katan must always be clean and, in reverence for its sanctity, should not be worn on the bare flesh but over an undershirt. If one of the ẓiẓiyot is torn, the whole tallit katan becomes ritually unfit (pesulah) until the torn ẓiẓit is replaced.
Shulḥan Arukh, oḤ 8:3, 6; Eisenstein, Dinim, 151–2.