T7 RNA Polymerase (NEB# M0251) and SP6 RNA Polymerase (NEB# M0207) and the HiScribe® T7 In Vitro Transcription Kit (NEB# E2030) can be used to make RNA probes. Increased levels of detection in nucleic acid hybridization can be obtained due to the greater stability of RNA: DNA hybrids with respect to DNA: DNA hybrids (1).