Ambion™ RNA Century™-Plus markers are a set of 100, 200, 300, 400, 500, 750 and Sevenin vitrotranscripts of 1000 bases. This product is an EtBr-stained, non-labeled product available in tubes containing 50 µg at a concentration of 1 mg/mL. They are premixed, stain equivalently on 5% polyacrylamide/8 M urea gels, and can be used as RNA size standards in denaturing gel electrophoresis. 1–2 µg (2–4 µL) of marker produces 7 distinct bands on a TBE-Urea acrylamide gel stained with EtBr. Additionally, the markers have been tested to be nuclease-free and stable overnight at 37°C.