Modvat credit availability on packaging materials clarified; credit may be used for duty on specific-rate finished products. Where finished goods attract a specific rate of duty, Modvat credit on duty paid for packing materials (e.g., glass bottles, tin containers) used in packing those goods is admissible for payment of duty on the finished products, because inclusion of the packing material's value in the product's assessable value is immaterial when a specific rate applies.