Rollers for lawn machines are used to create a striped pattern on the lawn. These rollers have grooves or ridges on their surface that help to evenly distribute the weight of the machine and create a consistent pressure on the grass. As the lawn machine moves over the grass, the grooves in the roller bend the grass in one direction, while the areas between the grooves remain upright. This creates the desired striped effect on the lawn, giving it a neat and professional appearance. Additionally, the grooves also help to improve traction and prevent slippage of the lawn machine, especially on uneven or sloping terrain.