Modern high speed fuses are made in many shapes and sizes, but all have the same key features. Although all fuse components influence the total fuse operation and performance characteristics, the key part is the fuse element. This is made from a high conductivity material and is designed with a number of reduced sections commonly referred to as "necks" or "weak spots." It is these reduced sections that will mainly control the fuse's operating characteristics. The element is surrounded with an arc-quenching material, usually graded quartz, that "quenches" the arc that forms when the reduced sections melt and "burn back" to open the circuit. It is this function that gives the fuse its current-limiting ability. To contain the quartz arc-quenching material, an insulated container (commonly called the fuse body) is made of ceramic or engineered plastic. Finally, to connect the fuse element to the circuit it protects there are end connectors, usually made of copper. The other fuse components vary depending on the type of fuse and the manufacturing methods employed.