These bags are made from woven polypropylene. They are not air tight, although they are close to it.
Woven polypropylene combines the advantages of high strength and low weight to make it an ideal packaging solution for many products. Polypropylene bags are one of the lowest cost types of packaging and polypropylene is also easy to reuse. Its woven construction minimizes damage if the filled sack is snagged.
These sacks are used in a multitude of industrial and agricultural applications, for example, the smaller sizes are suitable for sandbags or rock samples.The mid sizes are used for rice, grain and shipping bags.
The largest available poly bag is a mega size. These bulk bags are three dimensional and hold a cubic meter of fill up to 3000 lbs. They come with lifting straps in duffel top or spout top designs and discharge chutes.