Hanging tags for the identification of metal racks and other containers stored long-term in liquid nitrogen Dewars and ultra-low temperature laboratory freezers. Each Cryo-ID-Kit™ includes 12 plastic Cryo-Cards™ with connection hooks and thermal-transfer cryogenic labels. The supplied NitroTAGTM labels can be printed on using all common thermal-transfer barcode printer brands with alphanumeric text, serialized information, as well as 1D and 2D barcodes. The labels can also be inscribed with permanent markers.