ABclonal First Strand Synthesis Module (Stranded) (AB-RK20342) is designed for RNA fragmentation and first strand cDNA synthesis in RNA-seq library construction. The second strand cDNA can be directly synthesized without purifying the first strand cDNA product. The RT Strand Specificity Reagent in this module contains Actinomycin D to improve strand specificity and can be used with ABclonal Second Strand Synthesis Module (Stranded) (AB-RK20343) to make strand-specific RNA libraries. In addition, Frag/Elute Buffer employs Mg²⁺ at high temperature conditions to fragment the RNA. Therefore, the RNA sample cannot contain metal ions such as Mg²⁺ or a metal ion chelating agent such as EDTA, which may affect the fragmentation size of RNA.