The original PL2303-DB9 was revised with an updated chipset in April of 2021. The original version of PL2303-DB9 featured a Prolific PL2303HXD chipset which was discontinued by Prolific in 2020. This version of the adapter featured a blue plastic casing as shown below:

The adapter has since been updated to use the more recent PL2303GT chipset from Prolific. This chipset offers many of the same features as PL2303HXD and is a drop-in replacement in most applications. The new version of the adapter features a grey plastic casing as shown below:

If you have any questions about the different versions please contact us at support@plugable.com and we'll be happy to assist.