They are great. Keeps grease and parts of food from falling past the grate preventing unnecessary flair ups and uneven food cooking. If you BBQ burgers, sausages, wings or other fatty meats, the grease remains on the mat and cooks perfectly. That said, you lose a bit of the grill marks if you like that look. To me, the benefits outweigh the look of grill marks so I gave it 5 stars.