The PBac{RBr} transgene represents the reconstituted transgenic element generated in vivo when FLP is used to induce recombination between the FRT sites of two insertions of the PBac{RB} transgene. Like PBac{RB}, PBac{RBr} contains (from 5' to 3'): a w^+mC marker, a single long (199bp) FRT site and a splice acceptor site (in the opposite orientation to the w^+mC marker). The presence of the splice acceptor site in addition to the w^+mC marker results in the element being mutagenic in both orientations. PBac{RBr} is typically generated as part of a deletion-generation strategy; when the two insertions are in trans and are in the appropriate relative orientation, FLP-mediated recombination can result in deletion of the genomic region between the two original insertions along with production of the reconstituted PBac{RBr} element at the recombination point.