Permanent twisted-pair cabling, also known as vertical or horizontal cabling, is used above ceilings and in cable ducts, connecting to the wall outlet at the workplace. From the outlet, patch cables are used to connect laptops, docking stations, or PCs. The fixed cabling is typically installed by professionals, which is why it is also referred to as installation cable. Solid cabling contains more copper than patch cables, making it ideal for bridging larger distances. Due to the higher copper content in a solid cable, fixed cabling is also referred to as solid cabling. Solid permanent cables are less flexible than patch cables, which are also known as zip cords.