If you need to add a list of custom specifications for your product, you can create them in Products > Product Specifications > View Product Specs. Click on the Create Product Specification button to add a new one.
Assigning Specifications to Products
To assign specifications to products, just click on Products > Manage Products > View Products and edit the product that you want. Select the Specifications tab and click on Assign Product Specifications to add new specifications. Once it is added, you can set the specifications value for this product.