If you are doing cutting that is being measured by your ruler, consider turning over your green olfa mat and using the back. Both sides are good. Threre are some times when you need the grid for cutting, but often you do not. That way your mat may last twice as long. I've had mine for years. If you have an old one, don't throw it away, use the back.
My big problem was getting it home w/o having it bend. After having one bend (it was laid on top of groceries, very carefully so it was basically flat, but it was unusable when we got home (3 hours... we lived in the mountains). Next trip down my husband went into JoAnn's and told them we wanted a new one WITH THE BOX in which they are shipped to the store! They dug in the back room, found the box and gave it to us. Thank goodness they were 40% off. What an expensive lesson.