Antair Devolinx STE-502C 2-Port RS-232 Serial Server

MOXA OPT8-RJ45 8 Port Connection Box DB62(M) to 8 x RJ45 (8-pin) RS-232

Kentek DB25 4 Way Data Transfer Switch Box RS-232 Parallel Rotary PC MAC Printer

Waveshare RS232 RS485 to RJ45 Ethernet Serial Server Dual Ethernet Ports W/ Case

1x4 or 4x1 - 4-Port AB Manual Sharing DB9 RS232 Serial Switch 4-Way Selector Box

Kentek DB9 Female 4 Way Data Transfer Switch Box RS-232 D-Sub I/O ABCD Port PC

StarTech.com 4 Port Serial Hub USB to RS232/RS485/RS422 Adapter ICUSB234854I

KNTK 4-Way DB9 Data Transfer Switch Box Rotary Printer RS232 Serial RS-232 9-pin