Cryoguard™ Corporation manufactures indicators that report thermal exposure at six pre-set “signal” temperatures between ‑40°C and ‑150°C. Indicators irreversibly change color from green to red within 1-2 hours at their signal temperature and within minutes at 10°C above their signal temperature. At 25°C below their signal temperature indicators remain green; thus, providing quality assurance that the monitored material was never thermally compromised. Cryoguard indicators currently assure the quality of stem cells, sperm, oocytes, blood plasma and premixed epoxy adhesives during shipping, storage and handling by laboratory personnel, shippers and custom inspectors. Since a green indicator unambiguously signals that the monitored material is safe to use, Cryoguard indicators can provide a hassle free alternative to data loggers. Cryoguard Corporation also provides freezer boxes that have openings on their sides for viewing indicators to facilitate verification that the boxed material was never thermally compromised during handling, power outages and coolant depletion.