The most fundamental of Chroma's filter sets. These sets were designed primarily for viewing the fluorescence of single fluorochrome. All of these sets contain longpass emission filters. Longpass emission filters cannot exclude the fluorescence of a second fluorochrome which may also be excited. For instance, blue light, which is the primary excitation color for FITC, will also excite, albeit slightly less efficiently, than TRITC. A longpass emission filter will be unable to exclude the fluorescence of TRITC. Most of the barrier filters of our Basic sets are made from absorptive glass.