Monster Dab Rosin Bags are made of nylon and designed to withstand the heat and high pressure needed for extracting solventless rosin using a rosin press. The nylon material can stretch without breaking and able to retain its shape after pressing. This means that it's capable of holding more material than other options. It's also FDA approved and safe to use in consumable products. Monster Dab Rosin Bags are the highest quality and lowest cost solution for rosin extraction.