Manhattan USB-A to 4x Serial Port Converter, Male to Male, Serial/RS232, MosChip MCS7840, Automatic IRQ and I/O address selection, Bus powered, Silver, Boxed | www.uk.shi.com
AX78120 - USB 2.0 to Multi I/O (1S or 2S) Controller | ASIX
Manhattan USB-A to 4x Serial Port Converter, Male to Male, Serial/RS232, MosChip MCS7840, Automatic IRQ and I/O address selection, Bus powered, Silver, Boxed | www.uk.shi.com
MCS7840 Datasheet(PDF) - List of Unclassifed Manufacturers
USB to 4 Ports RS232 Converter - Metal Case - RS-232 Interface via DB9 Connector - ASIX MOSCHIP MCS7840 Chipset : Amazon.com.be: Electronics
AX78140 - USB 2.0 to Multi I/O (4S, 2S+1P) Controller | ASIX
MCS7840 Datasheet - USB 2.0 to Quad Serial Controller