This is not a standard adapter and will not work as a standard port adapter. It is specially wire for loop back testing software (not included). It is designed to test a DB9 port or a DB25 port so when you use it you only hook up one side or the other to you computer.Designed to troubleshoot and diagnose your DB25 or DB9 serial ports. Each order Contains 1PC (One Piece). Picture demonstrated adapter's front and back connection. Standards: UL, CSA, ISO 9001:2000 manufacturer