The Model 520G is a complete high pressure gradient HPLC system. The system includes one Model 521, one Model 520, and all necessary electrical and plumbing connections. UHPLC (Maximum pressure: 15,000 PSI) is available for Analytical flow. Also Titanium pump heads and Biocompatible PEEK pump heads are available for all flow ranges. Titanium pump heads and Biocompatible PEEK pump heads are not listed below, please contact us for ASI part numbers. Dual primary pump heads are also available, please contact us.