I searched the West Mountain Radio web site but could not find any info about the Pro USB. All I could find on the web was this: http://www.universal-radio.com/catalog/tnc/2223.html 73 - Jim AD1C -- Jim Reisert AD1C, 7 Charlemont Court, North Chelmsford, MA 01863 USA +978-251-9933, <jjreisert at alum.mit.edu>, http://www.ad1c.com