scFv(antiHA-X15F11) is an engineered single-chain variable fragment antibody (scFv) that binds the Tag:HA epitope. scFv(antiHA-X15F11) is a chimeric 'frankenbody' that was generated by grafting all six complementarity determining regions (CDRs) from the 12CA5 scFv (an scFv that binds the Tag:HA epitope) onto the scaffold of the 15F11 scFv (an scFv that has been used successfully for live-cell imaging) (PMID:31270320).