Extremely thermostable proofreading DNA polymerase blend, formulated for efficient site-directed mutagenesis and synthesis of DNA products up to 20 kb. The enzyme catalyzes the polymerization of nucleotides into duplex DNA in the 5’→3′ direction in the presence of magnesium ions. The enzyme exhibits the 3’→5′ proofreading activity, resulting in over 10-fold higher PCR fidelity than possible with Taq DNA Polymerases. The constituent of PfuPlus! DNA Polymerase, the polymerase-enhancing factor, enhances PCR product yields and increases target length capability of Pfu DNA Polymerase. Enhanced performance of PfuPlus! DNA Polymerase allows to use fewer PCR cycles and lower DNA template concentrations when compared to Pfu DNA Polymerase. PfuPlus! DNA Polymerase is recommended for use in high-fidelity PCR, PCR of GC-rich sequences or problematic secondary structures, site-directed mutagenesis and cloning of blunt-ended PCR products. The enzyme is also recommended for general use in PCR and primer extension reactions at elevated temperatures to obtain a wide range of PCR products up to 20 kb.