A symmetric dicing machine (Gan, Tropea, Austin, Court, Waugh, and Ji. Cell 2006; 124:355-366. Abstract; Gan, Shaw, Tropea, Waugh, Court and Ji, Mol. Microbiol. 2008; 67:143-154. Abstract). The highly symmetric structure of an RNase III-product complex reveals that the dimerization of the two endoNDs is essential for the formation of two RNA cleavage sites precisely arranged to produce the characteristic 2-nucleotide 3´ overhang of RNase III products. The two endoNDs are shown as molecular surface; the two dsRBDs are illustrated as ribbon diagrams (helices as spirals, b-strands as arrows, and loops as pipes). The two subunits are colored in cyan and orange, respectively. The Mg²⁺ ions are indicated with black spheres; the two cleaved RNA strands are shown as tube-and-stick models in blue and red, respectively.