For details on how product recommendations work in Clientbook please view the article titled "How Product Recommendations Work"!
In RAIN and Jewel360, there's a product field called "Manufacturer Number", which is used to generate your product recommendations in Clientbook.
To ensure accurate recommendations, make sure this field only includes the exact vendor item ID (also known as the Vendor Style Number or Manufacturer Part Number/MPN).
For more details on how to add a new product in RAIN and/or Jewel360, check out the article "Product Information Tab".