By definition, Single SKU Bundles only have one SKU to represent each product within the bundle. In order to display the contents of the bundle, Bundle Builder displays each product as its own line item property.
Displaying products as line item properties allow customers to see their bundle's contents listed in the cart, email receipts, and order confirmations - and some merchants use this information to help fulfil their orders.
In order to display line items properties in the cart and in email notifications:
Within Bundle Builder, go to Settings.
Scroll down to Line item properties, and select Enable.