AGB stars are typically long-period variables, and suffer mass loss in the form of a stellar wind. For M-type AGB stars, the stellar winds are most efficiently driven by micron-sized grains. Thermal pulses produce periods of even higher mass loss and may result in detached shells of circumstellar material. A star may lose 50 to 70% of its mass during the AGB phase. The mass-loss rates typically range between 10−8 to 10−5 M⊙ year−1, and can even reach as high as 10−4 M⊙ year−1.