Got a reply from GRE. They say it works with the PRO-106. Email quote below:
Hello John,
Thank You for contacting GRE.
Yes the P/N: 100-010 will work for RS PRO-106 Scanner. The PRO-106 has the same engineering as the PSR-500 with a different cosmetic.
Feel free to contact me should you have any further questions.
Regards,
Raj Gounder