Laser Components GmbH has expanded its Count series single-photon counting modules to include the new CountBlue devices that combine the low count rates of existing modules with higher detection efficiencies at shorter wavelengths. More than 60% of incoming photons can be detected at 405 nm, more than 65% in the green, and more than 50%, typical, in the red. The semiconductor design ensures stable count rates and zero bi-stability. The good short-wavelength performance renders the modules suitable for use in a variety of applications in fluorescence spectroscopy and analysis, time-resolved single-molecule detection, particle sizing and confocal microscopy. The modules feature a robust design and are mechanically compatible with other commercially available photon-counting modules. A fiber connector is available as an option.