i-pfu DNA Polymerase is a typical heat-resistant proof-reading enzyme with 3'- 5' exonuclease activity. It has high fidelity and guarantees an error rate of 1x10-6 (one error rate per 13,000 base pairs). The proofreading activity of i-pfu DNA Polymerase results in PCR products with more accurate base sequences than when using Taq DNA Polymerase. When using i-pfu DNA Polymerase, DNA fragments longer than Taq DNA Polymerase (up to 30 kb) can be amplified. Due to these properties, i-pfu DNA Polymerase is widely used in experiments in which high accuracy is required, such as gene cloning and expression. Unlike Taq DNA Polymerase, this i-pfu DNA Polymerase produces blunt-end amplification products.