The pex2s553s 2 port pci express serial card lets you add two esd protected rs232 ports with 5v or 12v selectable power output through a pci express slot ideal for industrial environments this 2 port serial card offers built in 15kv esd protection which helps prevent damage to connected devices in the event of line surges and electro static discharge an extended operating temperature range 30degc to 75degc also helps to ensure performance in harsh environments for devices that require add