Description: The Concentrators combine the excellent protein retention of regenerated cellulose membranes with a significantly faster concentration time to give optimized concentration of protein samples. The concentrators delivery quantitative recover of micrograms of retained protein (>90%) and provide four times more buffer exchange in a single spin (1000x concentration factor). Available in five Quantitative Molecular Weight Limit Membranes 5k Da, 10k Da, 30k Da, 70k Da and 150k Da.