MBP Screw Cap Microtubes with Caps by Molecular Biology Products are polypropylene tubes supplied with clear O-ring screw caps in 0.5 mL, 1.5 mL and 2.0 mL, conical or self-standing. Sterile tubes come with attached caps, 100 per bag, and a non-sterile 2.0 mL conical version is packed 500 per unit. Tubes are rated to 20,000 × g and certified RNase-free, DNase-free and nonpyrogenic.