Sunroof systems on passenger cars are modules for increasing comfort. Depending on the model, different roof systems can be installed that contribute to improving all-round visibility, the supply of fresh air and the incidence of light. Examples are sliding roofs, panoramic roofs, folding roofs or convertible roofs such as soft tops and lined fabric roofs. Unlike fixed roof elements and removable hard tops, they have an adjustment function. The ease of operation depends on the model; analogous to the opening/closing of the vehicle roof, the engagement and locking can be done manually or automatically at the touch of a button, as can the necessary adjustment of the window position. All soft tops consist of the outer shell, the movable and, depending on the model, motor-driven substructure and an inner roof skin. Opened roof systems disappear under a cover or can be lowered into the boot. As a central component of the vehicle's skyline, roof systems must also be considered from a design perspective. Solar and lightweight modules in roof systems are current developments. Specialised manufacturers of roof systems supply the automotive industry and passenger car OEMs to mount the modules on the respective convertible models. Retrofit roof systems are also available on the market.