RS232 click - features a standard RS232 DB9 port and a MAX3232 IC
Insignia™ 1.3' USB-to-RS-232 (DB9) PDA/Serial Adapter Cable, with Prolific Chipset Black NS-PU99501 - Best Buy
Tripp Lite RS232 to USB Adapter Cable with COM Retention (USB-A to DB9 M/M), FTDI, 5 ft. - USB / serial cable - USB to - U209-005-COM - USB Cables - CDW.com
USB-C to Serial Adapter, RS232
Amazon.com: DB9 Serial RS232 to RJ12 6P6C Adapter Cable for APC PDU 940-0144A : Electronics
Serial Adapter (RS232 to RS485) - Micro Connectors, Inc.
USB to RS-232 DB9 1-Port Serial Interface Adapter - Sealevel