Easy-to-read black graduations offer accurate reading to ±2%; the 15-mL tubes feature increments of 0.5 mL while the 50-mL tubes have increments of 2.5 mL. Frosted writing surface allows for permanent identification and labeling. Tubes are offered in either non-sterilized or sterilized versions, are nonpyrogenic, and certified RNase-, DNase- and DNA-free.Available in cardboard racks or in resealable zip-top bags. These centrifuge tubes are non-sterile and come in a bulk case of 500 tubes. Safely withstands temperatures down to -80°C Disposable polypropylene tubes are autoclavable to 250°F (121°C). Can be safely stored in freezers down to -112°F (-80°C). Caps with recessed lid and sealing ring prevent leaking Red Cap