The NEBNext UltraExpress RNA Library Prep Kit has been optimized for streamlined library prep processing with one adaptor concentration and one PCR cycling condition used for all samples within the starting amounts of 25-250 ng of total RNA. The NEBNext Ultra II Directional RNA Library Prep Kit has more customized conditions based on input amount, more steps and cleanups, a longer workflow time, and a broader input range recommendation (10 ng – 1 µg total RNA).
Both kits produce high yields of high-quality libraries, but we recommend choosing NEBNext UltraExpress RNA for all of your standard samples within the stated input amount range, where speed is paramount. We recommend choosing NEBNext Ultra II Directional RNA for more complex and precious samples.
