0.12g Biodegradable airsoft BBs are made from a special blend of materials that are designed to break down over time when exposed to the environment. Some fields and venues may require the use of 0.12g biodegradable airsoft BBs at their games or events to avoid long-term environmental impact due to the difficulty of cleaning up the BBs after play. 0.12g Biodegradable airsoft BBs are best stored sealed in a cool, dry place. With proper storage these BBs can last for years!