Isotech has a wide range of Dry Blocks to suit probes requiring a large immersion depth. These products feature large and deep calibration volumes. As such they are less portable then the earlier Dry Blocks but have higher capacities and retain outstanding temperature uniformity, this uniformity is so good that these larger products are also featured in DataBook 2 as apparatus for Secondary Laboratories to realise the Fixed Points of ITS-90.

For comparison calibration the Oberon should be used with an insert. The insert has six pockets 8mm diameter by 160mm deep which is suspended from the top of the heatpipe so that the height is user adjustable. For flexibility an accessory can be added for blackbody use. The Oberon uses a specially designed stress free isothermal heat-pipe as its furnace that ensures a very low thermal gradient along the furnace core.

The heat-pipe is designed so that the inner wall is not subject to thermal expansion stresses from the outer wall before the heat-pipe reaches conduction temperature. The working fluid is permanently and safely sealed within the plasma-arc welded enclosure.