BHQ®-3 (Figure 1) stands for Black Hole Quencher 3 and it consists of a dark quencher, often used in dual-labelled probes. As dark quenchers, Black Hole Quenchers absorb energy without emitting fluorescence. They are in fact non-fluorescent chromophores.
Figure 1. Structure of 5'-BHQ®-3 (R = sequence).
metabion offers BHQ®-3 modification in its DNA portfolio: