BHQ™ Probes are traditional, linear, dual-labelled FRET probes, typically 20 to 30 bases in length, with a fluorophore and quencher covalently attached to the 5' and 3' ends, respectively. Fluorescence is released through the 5' exonuclease activity of Taq polymerase, which cleaves off the fluorescent dye upon the probe's hybridisation to its complementary sequence. BHQ Probes are ideal for detecting the presence and quantifying the amount of specific target sequences.