An Aerial Lift or platform is a mechanical device used to provide temporary access for people or equipment to inaccessible areas. These inaccessible areas are normally at a height that is not accessible by the use of a normal ladder. There are various types of these devices including the cherry picker and scissor lift. They are generally used for temporary, flexible, access purposes such as construction and maintenance but are also used extensively by the fire brigade in emergencies and this is what distinguishes them from such equipment as elevators which are a permanent installation. They are designed to lift weights of normally less than a ton although some have a higher safe working load. They are usually capable of being operated by a single person but also have a set of controls at the base so as it can be operated by a person on ground level. Depending on the application these work platforms are normally equipped with various electrical outlets and compressed air connectors for power tools. They can also be adapted to carry specialised equipment which can be used for carrying awkward objects such as window frames or glass.