For a general guideline, the Halo® hair extension should sit easily across the crown of your head. It need to gently touch your head, and may not move when you shake your head. Click the link to find out a video clip of how to decide on your wire size. https://rowankeuos.xzblogs.com/63455784/the-smart-trick-of-how-to-place-tape-in-hair-extensions-at-home-that-nobody-is-discussing