These shielding antistatic bags feature a zip closure, making them reusable. They utilize the principle of the Faraday cage, allowing for use both inside and outside an ESD protection area (EPA). Any static charges are shielded and dissipated from the contents – the "S" class (Shielding) provides the highest ESD protection for valuable components. The slightly transparent cover allows the contents to be seen from the outside without having to open the bags. The bags are made from various antistatic plastic layers that surround a shielding aluminum layer.