MBP Screw Cap Microtubes without Caps by Molecular Biology Products are polypropylene screw-thread tubes in 0.5 mL, 1.5 mL and 2.0 mL, with conical or self-standing bottoms in natural or amber. They are rated to 20,000 × g and pair with MBP O-ring screw caps in six colors for storage, freezing and shipping. Tubes are non-sterile and packed 500 per unit, 8 units per case.