Aten US-421A - 4-Port USB 2.0 Peripheral Switch The US421A is a 4-port USB 2.0 Peripheral Switch that allows up to 4 computers to share the use of a single USB peripheral device (such as a printer, scanner, mass storage drive, etc.) on a one-at-a-time basis. The peripheral focus can be given to a computer manually by using pushbuttons on the switch, using the software-based configuration utility, or by the Auto Switch function. Compatible with both Windows and Mac, and with multifunction printer support, the US421A is the ideal way to share the latest USB 2.0 peripherals in a multimedia office environment.