The WarmStart Colorimetric LAMP 2X Master Mix is an optimized formulation of Bst 2.0 WarmStart DNA Polymerase and WarmStart RTx in a special low-buffer reaction solution containing a visible pH indicator for rapid and easy detection of Loop-Mediated Isothermal Amplification (LAMP) and RT-LAMP reactions. This system is designed to provide a fast, clear visual detection of amplification based on the production of protons and subsequent drop in pH that occurs from the extensive DNA polymerase activity in a LAMP reaction, producing a change in solution color from pink to yellow (an overview of LAMP and primer design can be found in our video library, https://www.neb.com/tools-and-resources/video-library). This mix can be used for any LAMP or RT-LAMP reaction and requires only a heated chamber and samples, with readout of positive amplification judged by eye in 15–40 minutes.