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