EMD MILLIPORE UFC501096 Amicon Ultra Centrifugal Filter Unit with Ultracel-10 Membrane, Clear, 0.5 mL Volume, 1 sq. cm. Filtration Area, 10.8 mm Diameter x 49.9 mm L: Amazon.com: Industrial & Scientific
Millipore UFC805008 Regenerated Cellulose Amicon Ultra Centrifugal Filter Unit with PLQK Ultracel-50 Membrane, 4mL Capacity, 50kDa NMWL, 17.3mm Diameter x 124mm Length, 3 sq cm Membrane (Pack of 8): Science Lab Centrifugal