How does one carry a key on Shabbat without an eruv?

Greetings, According to the Ashkenazi custom, if the key serves as a buckle for a belt, it is permitted to carry it on Shabbat in an area without an eruv. For example, one can pass a string through the hole at the top end of the key to the midpoint of the string and tie the two ends together in a bow (not a knot), even on Shabbat, and wear it by tightening the teeth of the key within this bow. However, if the key hangs on the belt and does not function as part of it, it is forbidden to go out with it on Shabbat (see Rema, Orach Chaim 90:11; Mishnah Berurah 90:45; and Shmirat Shabbat Kehilchatah, Part 1, Chapter 18, Section 49). This leniency applies only if one is not wearing an additional belt (see Rema ibid., section 36, and Mishnah Berurah section 133), and there are further details regarding how to use the key when leaving and entering the house (see Shmirat Shabbat Kehilchatah, ibid., sections 50–59). According to the Sephardi custom, there is no permission to carry the key even if it serves as a belt buckle. Nevertheless, one should not protest those who are lenient when there is no alternative (Kitzur Shulchan Aruch, Yalkut Yosef, ibid., section 59). Blessings, Hillel Meirs