Stretching is usually done in small increments to minimize the potential for damaging the healed fistula or creating scar tissue. In North America, most stretching methods go up by a single even-sized gauge increment at a time. 0g (8 mm), is generally considered to be "the point of no return": a hole larger than this size will rarely close to a standard piercing size. Since each body is different, any stretched piercings, no matter the size, should be approached as a permanent body modification. In Europe and most of the rest of the world, jewelry is metric, but the increments between standard sizes are similar.