This Nalgene® cryogenic vial closure coder is green and is made of polystyrene. It fits into the top of Nalgene® cryogenic vial closures (except Cat. No. 5005-0015). It provides quick visual identification of specific vials to simplify inventory maintenance. WARNING! Do not use cryogenic vials for storage in the liquid phase of liquid nitrogen unless correctly sealed in Nunc CryoFlex™ tubing. Such use may cause entrapment of liquefied nitrogen inside the vial and lead to pressure build-up resulting in possible explosion or biohazard release. Use appropriate safety procedures as outlined in the NALGENE Cryopreservation Manual when handling and disposing of vials. Request Lit. No. 10096 or download a copy from www.NALGENElabware.com/techdata/technical/manual.asp. Color: Green. Material: Polystyrene. 100/Pack; 500/Case. Nalgene® #: 5045-0004.