USB to RS232 DB9/DB25 Serial Adapter - Serial Cards & Adapters | StarTech.com
D-subminiature - Wikipedia
USB-A to Serial Adapter Cable - RS232, DB9, 5-ft. | Eaton
Amazon.com: YIOVVOM Connector DB9 RS232 D-SUB Male Serial Adapter 9-pin Port Adapter to Terminal Connector Signal Module with case(Male Connector, DB9 5+5 with case A) : Electronics
10pcs Diy D-sub Connector 9 Pin Rs232 Serial Port Connector Db9 Male Plug Shell Plastic Solder Wire Type Nut Screw Adapter - Connectors - AliExpress
D-subminiature - Wikipedia
Ltvystore RS232 Parallel Serial Port DB9 9 Pin D Sub Male / Female Connector + Metal DB9 Shell Cover, Pack of 4