Touring sound systems have to be powerful and versatile enough to cover many different halls and venues, and they are available many different sizes and shapes. Touring systems range from mid-sized systems for bands playing nightclub and other mid-sized venues to large systems for groups playing stadiums, arenas and outdoor festivals. They also need to use "field-replaceable" components such as speakers, horns, and fuses, which are easily accessible for repairs during a tour. Tour sound systems are often designed with substantial redundancy features, so that in the event of equipment failure or amplifier overheating, the system will continue to function. Touring systems for bands performing for crowds of a few thousand people and up are typically set up and operated by a team of technicians and engineers who travel with the performers to every show.