Does the use of metal snaps to fasten the two-piece Ihram garment (loincloth and upper covering) and a third piece as underwear make the garment impermissible, and is it not allowed to wear the third piece?

Briefly, undergarments that resemble an izār (lower garment) and are wrapped around the body, not tailored to fit a specific limb, are not among the prohibited items in Ihrām. However, if they are tailored to fit a specific limb and are fastened with snaps, they take the ruling of trousers and are not permissible for the pilgrim in Ihrām to wear. The presence of metal snaps to secure a ridāʾ (upper garment) is permissible, provided that the ridāʾ does not appear like a tailored shirt; nevertheless, it is better to avoid them.