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A PoE (Power over Ethernet) switch is a network switch that can supply both data and electrical power to devices over a single Ethernet cable.
The product pictured is a PoE Repeater, which is used to extend the range of a PoE connection.
The packaging indicates that it can extend a standard PoE camera connection up to 250 meters and an ordinary camera connection up to 260 meters.
PoE switches are commonly used for devices like surveillance cameras and wireless access points.