A maser found in the cool dusty envelope of a red giant star such as a Mira star that is undergoing mass loss. OH, H2O, and SiO masers are common around stars with oxygen-rich envelopes, while the rarer HCN masers are found around stars with carbon-rich envelopes. The OH–IR sources have oxygen-rich envelopes with a characteristic twin-peaked OH maser at 1612 MHz and strong infrared emission from the dusty envelope.