The dsRNA Ladder is a set of 7 annealed double-stranded RNA molecules produced by invitro transcription of 14 linear DNA templates. The ladder sizesare: 500, 300, 150, 80, 50, 30 and 21 base pairs. All have 2-base, 3´ extensions. The 80 base pair fragment is at double intensity to serve as a reference point. This ladder is suitable for use as a size standard in dsRNA and RNAi analysis on both non-denaturing polyacrylamide and agarose gels.