CoolLed Ltd. has released precisExcite, a LED light source for fluorescence microscopy that is suitable for working with live cell samples, fixed tissue sections, plant materials and drosophila larvae preparations. With a remote control pod, a mixing and collimating unit, and a pair of lightguides, the device has advantages over conventional light sources. It generates no radiant heat, can be controlled to avoid photobleaching, requires no bulb alignment and offers a lifetime of more than 10,000 h as compared with mercury lamps, which have a relatively short life. It produces three selectable wavelengths that match commonly used fluorescent dyes. The wavelength and power are highly repeatable and do not change with aging.