Traditional Moloney Murine Leukemia Virus Reverse Transcriptase (MMLV-RT) is not thermostable and can only maintain its enzymatic activity at relatively low temperatures (up to 50°C). However, for cDNA synthesis, a higher reaction temperature is desirable as it reduces RNA secondary structures which can inhibit reverse transcription and it minimizes nonspecific primer binding. 55C MMLV-RT has higher thermal stability and reduced RNase H activity, allowing very efficient first-strand cDNA synthesizes at temperatures up to 60°C which improves the cDNA yield from difficult RNA targets that require higher temperature to denature strong secondary structures.