The ATEN US421A is a 4-port USB 2.0 peripheral switch that allows up to 4 computers to share a single USB device, such as a printer, scanner, or storage drive. It features multiple port selection methods, including pushbuttons, a configuration utility, and an Auto Switch function, making it ideal for multimedia office environments. Compatible with both Windows and Mac, it supports transfer rates up to 480 Mbps and provides overcurrent protection.