Rectangular Connectors - Headers, Receptacles, Female Sockets, are a type of electrical connection that makes it possible to connect one device to another. In the broadest sense, they are used to connect the inside and the outside of a device. They are used in all sorts of ways, including connecting electrical components to one another, connecting shielding boxes to circuit boards, and linking cables to devices. The 71991-411H is a part of this type of connectors. It is a 20-pin male header that is typically used as a signal transmission between devices. It is used mainly for PC motherboards and routers. It has a series of pins on one side and the opposite side has a series of holes for the wires to be attached directly to. The working principle of the 71991-411H is quite straightforward. Each pin on the header has the ability to pass a signal from the connected device to the host board through the associated pin or port. The same can be done in reverse; the signal from the host board can be passed to the connected device. However, this signal is limited by the header’s configuration, meaning the number of pins and their individual connections. Due to the fact that the 71991-411H is a male header, it is usually used in conjunction with a female socket, which is designed to accept the pins from the header. The header is inserted into the socket, making a secure and solid connection. This allows for easy testing and experimentation, as connected components can be easily removed and replaced with new ones. The 71991-411H can be used in number of different application fields. Firstly, it is used in the area of communication. It is used in both wired and wireless communication such as home routers, LANs, WANs, and the like. Secondly, it is used for data transmission between devices such as computer, tablets, and mobile phones. Finally, it is used in fields such as automotive, medical, aerospace, and industrial applications.Overall, the 71991-411H is a popular rectangular connector designed for a wide range of applications. It is an easy to use and economical electrical connection solution. Its simple working principle makes it an ideal connection solution for a wide variety of electronic devices.