Our website provided a free download of Keyspan USB Twin Serial Adapter 2.1 for Mac. This free software for Mac OS X is a product of Keyspan.
From the developer:
Keyspan USB Twin Serial Adapter is the driver software that allows you to connect your Keyspan USB Twin Serial Adapter into your USB slot, allowing you to plug in hardware that requires the serial port such as StylWriters, Personal LaserWriters, HP DeskWriters, and more.
You may want to check out more software for Mac, such as IOGEAR Bluetooth Serial Adapter Configuration Tool, QuickTerm or TCP2Serial, which might be similar to Keyspan USB Twin Serial Adapter.
Network Tools
Device Assistants