Liquid Nitrogen Dewar Caps & Necktube Cores

Replace your broken or lost neck tube core. The dewars (except for the 4 liter size) come with a standard lid, also called the "neck tube core". It is both a mechanical cover for the opening and an insulating cover for the top of the dewar, but it is loose enough for the nitrogen to be able to boil away without pressure buildup. The small 4 liter dewar comes with what is called a "cap". So it is not necessary to purchase an additional one. However, often times customers prefer to order spare neck tube cores or caps because they modify them so that different kinds of samples can be suspended into the dewar and kept at cryo temperatures.