May one wear a mask on Shabbos and adjust the metal strip around one’s nose?
Background: It is forbidden to fix things on Shabbos due to the prohibition of Tikkun Keli. Thus, it is forbidden to even simply bend a needle back in shape due to the prohibition of Tikkun Keli. The question is thus asked as to whether due to this law it would likewise be forbidden to adjust the metal strip of a face mask to fit one’s nose on Shabbos.
The law: While bending the metal strip within the mask seems similar to bending the metal needle into shape, and therefore should be forbidden, in truth it is not similar at all. The prohibition of Tikkun Keli only applies when fixing an item from a broken state or at least enhancing it into a state that it will now permanently remain in. For this reason, bending a needle back into shape is forbidden, as when it is out of shape it is unusable, and its bending into shape is meant to be a permanent fix. However, the metal strip within the mask is not considered broken in its current state, and is meant to be bent back and forth as needed. Its adjusted state is also not necessarily permanent and can easily bend back and need readjusting. Thus, in conclusion it is permitted to wear a mask on Shabbos and adjust the metal strip around the nose. Just as it is permitted to adjust the cloth onto the face, so too the metal strip. This is similar to the allowance to bend the brim of a hat back into shape if it folded upwards on Shabbos, and doing so is not considered under Tikkun Keli, as it is meant to be adjusted to various directions and is not considered broken in its prior state. A similar idea can be found in the Poskim regarding the allowance to reinsert feathers that came out of a pillow, back into the pillow on Shabbos, and doing so does not transgress Tikkun Keli.
It is permitted to wear a mask on Shabbos and adjust the metal strip to fit one’s nose and doing so does not transgress Tikkun Keli.
 Admur 302:5; Rambam 23:4; Smak 280; However, see Rashi 73a that “One is only liable on the Gemar Melacha”
 Admur 340:18; M”A 340:11; See also 509:1
 Admur 340:14; Michaber 340:8