Mylar bags are opaque, made from metalised polyester. With Mylar bags, the air is removed by the addition of oxygen absorbers, also known as oxygen scavengers.

Using Mylar bags with oxygen absorbers removes up to 99.99% of oxygen. The best vacuum sealer machines only remove around 99.5% oxygen, making oxygen absorbers 50 times more effective. Mylar bags with oxygen absorbers will remove the oxygen, but not nitrogen or other gases, so the actually volume of gas in the bag will only reduce by approximately one fifth. Bacteria can only grow in aerobic (oxygen rich) environments, so the presence of nitrogen and other gases in the sealed bag will not allow bacteria to grow.

Mylar bags are also much ‘tougher’ and more resistant to gas permeability than vacuum sealer bags, due to their metalised nature. Mylar bags can be considered to be like a flexible aluminium can, protecting the contents from not just gas permeability, but also light, heat, pests and damage due to impact and environmental factors.

The bags are available with various openings: plain opening bags, zip-lock bags, and vac-seal bags for use with vacuum sealing machines. They come in 3 different sizes: 20 x 30 cm, 25 x 35 cm and 35 x 50 cm.