The Black Knot medical ID bracelet is one you can tie on and leave on. It is casual, simple and will pair perfectly with a comfortable lifestyle. They come in one size fits most. Size is determined by where you place the knot. We like to use a square knot which gives the bracelet a more finished look and is ultra secure. Simply ask someone to tie the knot while on your wrist or you may tie it yourself. Once the bracelet is on and you are comfortable with the knots tightness you may cut the ends or leave them. This medic bracelet will be your custom fit!