Protein concentrator Vivaspin 15R MWCO: 2,000dalton Filter materials: Hydrosart ( modified regenerated cellulose) Active Membrane Area: 3.9 cm2 Dead stop volume: 30ul Rotor Cavity: to fit 50 ml conical bottom tube Min.Effective Speed: 1,500g Recommended Speed: 4,000g Max.Speed: 6,000g Pack size: 48 (Non-sterile)