I have answered you in the support ticket.
Here is a code sample of how to retrieve the product thumbnail url.
// Get a Catalog Manager
CatalogManager catalogManager = CatalogManager.GetManager();
var products = catalogManager.GetProducts().Where(p => p.Title ==
//Create a new ProductImagepopulater
var productImagePopulator =
//Loop through the proudcts and get the product thumbnail
var productThumbnailUrl = product.ThumbnailUrl;
All the best,
the Telerik team
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