A snRNA:U6:96Ac ( U6:3 ) promoter drives expression of a triple-gRNA targeting EGFP, GFP and mTagBFP2, each preceded by a Drosophila tRNA-Gly (G) spacer. The (F+E) gRNA scaffold described in FBrf0241409 is used. This is followed by a Ubi-p63E promoter driving expression of mTagBFP2.