A pin header (or simply header) is a form of electrical connector. A male pin header consists of one or more rows of metal pins molded into a plastic base, often 2.54 mm (0.1 in) apart, though available in many spacings. Male pin headers are cost-effective due to their simplicity. The female counterparts are sometimes known as female socket headers, though there are numerous naming variations of male and female connectors. Historically, headers have sometimes been called “Berg connectors”, but headers are manufactured by many companies.