The Exo-Resistant Random Primer is a mixture of single-stranded random thio-oligonucleotides used for highly efficient random priming of various DNA synthesis reactions. Primer contains modified nucleotides that are resistant to 3’ → 5’ exonuclease activity of proof-reading enzymes as Pfu DNA Polymerase, Phi29 DNA Polymerase. All oligonucleotides in the mixture have free 5’ and 3’ hydroxyl ends. The concentration of Random Hexamer Primer is optimized for amplification with Phi29 DNA Polymerase (supplied in 20x concentrated solution).