To show that a product belongs to a particular product class, you need to go to the product's details and complete the assignment.
To assign a product to a product class:
In your store's Admin area, select a product from the product list, open its details, and click on the "Attributes" tab.
It will open a page where you can manage product class attributes for this product.
Click the "Global" link to access the subsection to manage the product's global and product class attributes on the page that opens.
In the "Global" tab, you will see whether the product already has a product class assigned.
In our case, no product class is assigned. To assign a new class, click the "Change" button:
It will expand a section with a drop-down box titled "Product class."
From the list in the "Product class" drop-down box, select the name of the product class you would like to assign (If an appropriate product class does not exist yet, select the "New product class" item to add it):
Click the "Save changes" button to apply the selected product class name:
The product class has been assigned to the product and all product class attributes configured for it.
The product class attributes that are available for this product class are listed below the product class name.
Product class attributes must have at least one attribute option enabled to be considered configured and working. Therefore, once the related product class attributes are assigned to a product, check that they have options enabled and configured correctly.
See the Managing Product Class Attributes guide for more info on the attribute options configuration.
If required, a store admin can add new, edit and delete existing product class attributes directly on the product details page after a product class has been assigned to the product.
Suppose any product attribute of the assigned product class comes with an undefined attribute's value option. In that case, a store admin must assign an option to the respective attribute value to become available in product details in the storefront.