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The Gemara (שבת, פ׳ במה בהמה) has lengthy discussions about animals going out with covers tied to their udders or other extremities, and repeatedly (briefly) mentions a Zav wearing a sac to catch his discharge. What about a Zavah or a Niddah with a "Moch"? Is there any Issur of carrying, or a rabbinic prohibition lest she later come to carry it? It seems to me that this is a different sort of device (not tied on), but serving the same purpose as the Zav's, and because it's not tied it could come loose, which is the concern mentioned for the other cases. But (as far as I see so far) it isn't mentioned.

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The Zav's sack seems more like a tampon than a moch. A moch isn't there for hygienic reasons. – Double AA Nov 30 '12 at 4:54
Yay! Yoatzot agree(s) with me yoatzot.org/question.php?id=482 – Double AA Nov 30 '12 at 4:56
Can you edit in a more specific daf (or range of dapim) where this discussion is found? – Double AA Nov 30 '12 at 5:03
Ahh I misunderstood the Zav case. Yes Rashi says it's for checking so should be parallel to Moch and we see both are prohibited to carry. – Double AA Nov 30 '12 at 5:38
^^^ same as above to @ShimonbM. As for your question to my question, that is a different "Moch". That's a tampon. – Seth J Dec 2 '12 at 3:33
up vote 4 down vote accepted

Rav Moshe Feinstein forbade it (IgM, OC 3, 47).

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A tip of the hat to The Rebbetzin's Husband for pointing me to this IgM. – msh210 Nov 30 '12 at 8:49
It's important to note though that he does suggest a possible heter, but prefers not to rely on it. – Double AA Nov 30 '12 at 9:33
@doubleaa, interestingly, whatever R' Moshe's reasons for rejecting the Heter (I haven't read the Teshuvah yet), Yoatzot (thanks for "suggesting" that site for this discussion, btw) recommends that a woman with a compelling need to go out seek a Heter to skip the "Moch" rather that a Heter to use one without an 'Eruv. – Seth J Dec 2 '12 at 3:40
@SethJ That sounds pretty reasonable as carrying on Shabbat would be an Issur Sekilah (and I agree with RMF that his svara is kinda weak), whereas in most cases performing a Moch Dachuk is somewhat of a chumra. – Double AA Dec 2 '12 at 4:48
@doubleaa, except that an 'Eiruv only works if carrying would be an Isur DeRabbanan. – Seth J Dec 2 '12 at 10:26

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