Halacha presents specific requirements regarding the positioning of the holes on the corners of the Talit, where the Tzitzit are tied to the garment. Namely, the hole must be positioned no further than 3 "thumbs" from either edge of the Talit. The measurement of a "thumb" is generally assumed to be 2 centimeters (.787 inch), and thus the hole on the corner of one's Talit must be positioned within six centimeters (2.36 inches) from both the length and width of the garment. Chacham David Yoseph, in his book "Halacha Berura," adds that to satisfy all opinions, one should count 4 centimeters (1.57 inches) from the bottom of the Talit, and place the hole at that point, at the very beginning of the fifth centimeter (1.97 inches). Positioning the hole at this point effectively satisfies all views among the Poskim on this issue.
The Mishna Berura (11:54) makes a very important point regarding this Halacha. Tallitot generally come with decorative fringes along the sides. The Mishna Berura emphasizes that one must ensure that no fringes or strings protrude from the corners of the Talit. If there are fringes or strings extending from the garment at the corner, then their length must be taken into account when determining the correct position of the hole, the distance from the edge within which it must be situated. It will then likely turn out that the hole is not situated within the minimum required distance from the edge, thus rendering the Talit invalid.
Therefore, one must ensure when purchasing a Talit that the area of the corners is perfectly clear, without any strings or fringes extending from those areas.
