The aluminum cross bars on the roof rack feature T-slots to seamlessly mount compatible attachments such as ski racks, bike racks and cargo boxes. This roof rack is compatible with all Model 3 cars, regardless of configuration. This includes two cross bars with towers, one tower fitting kit, one key set and a copy of the installation instructions. The ultra-sleek attachment mechanism makes for easy installation at home while blending in seamlessly. Construction: Aluminum powder-coated cross bars; die-cast towers with integrated locks