The LineLink SA3 Modem Technology Concepts Inc Vintage External Data Fax Unit is a rare find, sealed and unused . This fax data switch unit, specifically designed for LineLink brand compatibility, represents a piece of computer history that could be of interest to collectors or those looking to restore vintage networking systems. With its unique design and functionality as an external data fax unit, this product offers a glimpse into the past of modem technology and provides a valuable addition to any computer component collection.