Of these 4 billion lb, only about 500 million lb (primarily from beverage bottles) were mechanically recycled into secondary items such as boat hulls, surf boards, carpet fibers and fiberfill for winter clothing(open-loop recycling), while the remainder was landfilled or incinerated. Mechanically recycled PET generally requires PET that is free from significant quantities of impurities such as dyes, coatings and other polymers (high-quality grades such as that found in beverage bottles) PET that is mixed with significant quantities of dyes, coatings, polymers, or other contaminants (e.g., PET that is used for audio and video tapes) is usually not suitable for mechanical recycling and is landfilled or incinerated.