The radiation amplified by hydroxyl masers is the radio continuum of its host. This continuum is primarily composed of synchrotron radiation produced by Type II supernovae. Amplification of this background is low, with amplification factors, or gains, ranging from a few percent to a few hundred percent, and sources with larger hyperfine ratios typically exhibiting larger gains. Sources with higher gains typically have narrower emission lines. This is expected if the pre-gain linewidths are all roughly the same, as line centers are amplified more than the wings, leading to line narrowing.