in the voids between the cargo items. Dunnage bags can be used in all modes of transportation; road, railway, ocean or air. Originally rubber bags were used to brace pallets inside trucks. They evolved into kraft paper bags with a plastic-bag interior. As metal strapping has become less popular, many companies now use polyethylene- or vinyl-based bags because of their low cost. It is important to match the size of the bag to the void. Starting in the 1950s, several US railroad freight carriers began rostering boxcars equipped with load-securing devices to prevent shifting during transit. These cars were usually labeled "Damage Free" or simply "DF". The interior equipment helped to eliminate the need for customer-supplied dunnage. In the 21st century, Amazon began air-filling dunnage bags on site during packing in order to minimize environmental impact, shipping weight, and cost of packing materials. Ships Dunnage for securing cargo in holds of ships has evolved from wooden boards forming "cribs" to modern mechanical, spring-loaded post-and-socket systems, exemplified by the "pogo sticks" used on US Navy Combat Logistics Force (CLF) ships which provide underway replenishment of stores, spares, repair parts, ammunition, ordnance, and liquids in cans and drums. Dunnage segregates cargo in the hold and prevents shifting of the cargo in response to ship motions. Shipbuilding During the shipbuilding process, dunnage is commonly used to describe items such as welding machines, hoses, ladders, and scaffolding which are not part of the ship and will not remain aboard after it is completed. Miscellaneous uses of term Outfitters and mule packers use the term dunnage when they transport freight, such as camping gear and food supplies, but do not carry passengers. In fishing net products "dunnage" may refer to a reinforcement of the edges of the net. It has historically been widely used in the United Kingdom for a sailor's personal belongings, as in, "Stow your dunnage and report to the First Mate". Many manufacturing facilities use the term dunnage to refer to the containers and packaging used for their finished goods. This can be anything from wood boxes or steel bins to wire baskets and plastic trays. Commonly this packaging is designed specifically to hold the product being manufactured and is proprietary to that manufacturing facilities requirements. On some vessels, it is used as a euphemism for human waste. See also Cushioning, package protection inside containers Ullage, unfilled space in a container References