This model has been designed mainly for use in cold water.
The MC7 diaphragm first stage comes with the standard issue antifreeze kit and the second stage is identical to the one used in the Ellipse Titanium.

The first stage of the Ellipse Alaska is the already famous and excellent Cressi MC7 model balanced diaphragm. It comes with the antifreeze kit, which provides an additional waterproof chamber, to screw onto the end of the first stage. This chamber ends with a silicon diaphragm on the outside that seals off the inside from contact with water, while still transmitting any pressure variation to the inner organs, thanks to the flexibility of the material. 
The antifreeze kit is composed of two main parts, both made from strong chrome-plated brass. There is a mushroom element inside, made from acetylic resin, which connects the external diaphragm to the internal one.

The use of the antifreeze kit completely eliminates any water seepage into the external part of the first stage, so not only does it prevent the formation of ice in this area, but it also prevents the formation of deposits and incrustations on the diaphragm and on the spring. This provides considerable advantages for divers working in mineral-rich water or with lots of suspension (archaeological sites, port works, caving etc...)