The manufacturers links are divided into those that primaraly manufacture fire alarm panels, fire suppression systems, fire detectors, fire sprinkler equipment, portable fire extinguishers, gas detection, and programmable logic controllers. While some of the manufactures are involved in multiple categories, they have been divided up into the categories for which they are best known. The fire sprinkler category includes are more diverse group of companies. Most fire sprinkler manufactures make only a partial segment of what is installed for these systems making it more difficult to divide them into specific categories.