50mL Metal Free centrifuge tubes in bags. Non Pyrogenic. Lot certified RNase/DNase free. Low Metal Certified to 1ppb of Calcium, Magnesium, Zinc, Iron, Manganese, Copper, Aluminum, Silicon, Nickel, Vanadium, Sodium, Phosphorus, Cobalt, Chromium, Potassium, Lithium, Lead, Selenium, Cadmium, Mercury, and Arsenic. Additional heavy metals have been tested for using the prescribed USP method and confirmed to have levels lower than 1 part per million (1ppm). 50 per bag. 10 bags per case. Sterile. Made in USA.