About Those Segula Rings
Many a blogger and his brother, most, if not all of whom have a more rationalistic bent, are intrigued/up in arms by the Segula rings that appeared in a Mishpacha Magazine ad. The ad advises using this segula, and it has haskamot from various Rabbanim in a Kabbalistic Yeshiva and most notably, Rav Moshe Shternbach, Shlit"a.
Some unfortunately are conflating the three issues involved: 1) whether the ad is advisable or not, 2) whether segulot that involve holy names should be used or not and 3) whether segulot are effective or not in general. I'm not going to give my own opinion in any of these issues, but I will try to bring some of the sources I found (not necessarily extensive) regarding this particular segula.
The Kav Hayashar says that this segula comes from R' Yoel Ba'al Shem of Zamost, and he says that it is effective for preventing Keri. The Hida says that this is good for traveling (and since he quotes the Kav Hayashar, he apparently means that it's good for traveling to prevent Keri). The Yesh Manhilin (סי' כ-כא) says that he actually wore one when he was younger on a finger on his right hand. (He also brings down a similar segula to wear a ring with different holy names, which should help prevent epilepsy in babies. The periodical Tzefunot has a page about a similar segula ring from the Ba'al Shem of Michelstadt.)
The Taharat Yom Tov, however, says about this segula "We have not merited to use holy names." Also, the Lubavitcher Rebbe says that there are numerous problems with this: 1) it may be an issue of Lo Yilbash (men wearing items designated for women), 2) it would be a problem where one may walk wearing such a ring with holy names, 3) the holy names themselves may be inaccurate since there may be errors in the books. See also Prof. Gedalia Nigal's article (which I see referenced, but could not find the text of online) "קבלה מעשית בפרנקפורט במאה השמונה-עשרה" in the periodical Sinai vol. 118 p. 91, available in Otzar HaHochma for those who have it (p. 295).