The usual way people roll up a yoga mat after using it was to roll from one end to another. This way the bottom side touches the top side and carries the dirt and whatever items on the floor into the mat. It's just not sanitary!!
By simply folding the yoga mat top side together first then roll up the mat would ensure the top side touches only the side you exercise on. However, if you fold the mat half way from the middle, one end is going to be further out than the other end when it's rolled up because the thickness of the mat.
My invention is to provide a guide line printed on face of the mat, so that it is easy to fold from the right place. The guide line would need to be adjusted per mat manufacturer. For example, the guide line for extra thick yoga mat (thicker than 6 mm) and mat with harder material will be further away from the grommet. And the guide line for extra long yoga mat (longer than 68″) would be closer to the grommet.
In addition, by providing a grommet with a string, it saves you from purchasing a mat sling to secure your mat when it's rolled up. The grommet is located on the top end, it also gives user a direction of which end you place your feet, or face on.
Top view of the invention. Locate a grommet at top edge of mat. Center of grommet is 1¼″ down from the edge. Guide line #1 is printed 5″ from top edge for 3 mm thick mat, guide line #2 is printed 6½″ from top edge from 6 mm thick yoga mat.
Side view. Fold the mat top side (the side was exercised on) together first. In this drawing, the bottom edge which was folding up aligned with guide line #2 for 6 mm thick mat.
Side view. As the mat was rolling up, the mat (upper layer) was pushed closer to the grommet.
Side view. When mat was fully rolled up, the mat (upper layer) stopped before the grommet opening.
Side view. Wrap the string around the roll and tie.