Packaging serves two main categories - consumer packaging which is designed for market appeal, convenience, and product protection from elements. Logistical packaging is critical for distribution and prevents damage during storage, transportation, and bulk handling. Packaging represents 5-30% of product value and is an important marketing and distribution element. Common unitization methods include containers, pallets, and slip sheets to group large numbers of products into convenient packs. Common packaging materials are corrugated fiberboard, steel, plastics, and wood.