This AB switch allows you to share two Mac serial devices such as modems and printers between two computers. It is guaranteed up to 10,000 switching cycles. When the computer on Port A is connected to the modem, the other computer is automatically transferred to the serial printer. This manual switch has metal case, heavy duty sealed rotary switch to prevent dust and moisture, gold-plated contacts and 5 Year Warranty. (Connectors: 4 Mini8 Female)