Durac, a part of H-B Instruments, manufactures liquid in glass thermometers ideal for measuring temperatures in freezers, ultra-low freezers and incubators. These thermometers come equipped with a glass bottle to store the sample and provide an accurate temperature reading without contaminating the sample. Made of lead-free glass, these H-B Durac thermometers contain an organic liquid, or EnviroKleen certified Enviro-Safe liquid, and feature permanently fused markings. Selected models also have a PFA coating to protect the glass and liquid in case of breakage.