SPINWIN^TM HOOKLOK Microcentrifuge Tubes are made from virgin, USP Class VI & US FDA 21 CFR compliant virgin Polypropylene. HOOKLOK Microcentrifuge tubes feature an additional HOOKLOK design that securely prevents cap opening during boiling. These are non-sterile, leak-proof, and autoclavable. They are free of detectable DNase, RNase, and Pyrogen. These tubes have moulded volume graduation along the length of the tube. They have good optical clarity and a uniform wall thickness. They can withstand up to 20,000 x g RCF. Perfect for versatile applications, they are used globally for storage, spinning down, reaction processes, and more.