These Dewars are designed for the storing of cryovials in racks containing 25-cell or 100-cell boxes in liquid nitrogen. Easy to operate, the snap on cap and necktube core assure positive closure and easy access without unnecessary exposures to the cryogen. Constructed from materials of the highest performance and quality including an aluminum exterior, these containers are not only rugged, robust, and dependable, but also have very high thermal efficiencies. Numbered rack system allows easy location and quick retrieval of samples. Limited opening maintain low vapor temperatures of -185°C and provides economical evaporation rates. A locking provision for the lid is supplied for added security. These units are backed by a one year parts and labor warranty and a three year vacuum warranty. Units come complete with stainless steel racks and either polycarbonate or fiberboard boxes.