Straight Flush is the single version of the famous Royal Flush dual overdrive. Using the GAIN toggle switch you can choose between the LOW Gain channel, the HIGH Gain channel. LOW channel is a low gain overdrive and is designed to create tube amp “early break-up” overdrive for rhythm tone, with tone clarity. HIGH channel is a medium gain overdrive and is designed to capture creamy and rich sound of an amp-like distortion crunch.