Hello @neumannsalva. It is a little bit complicated. Only when it is time to sew it you have to center it well ... I place it on a mannequin once it is sewn and then on the mannequin put, the amount of the center that I am going to sew is enough. Or you can do it with yourself by looking in the mirror ... there is also the other way to do it on the outside which is like this one in the photo ... This week I will do a video tutorial on how to make the V-neck on a shirt if it serves as Something I really like that you are interested in sewing and the support of commenting. Thank you Take care Greetings