The IHT Triple Stack is used to adjust your altitude. Breathing through a single mixer causes a modest drop in blood oxygen %. Breathing through 2 mixers (equal to about 10,000 feet) causes a drop in most people down to 90-92% blood oxygen after about 2 minutes. Three mixers it drops it down to 84-90% and 4-6 mixers drops it down to 65-84% blood oxygen, depending on the individual. Each session is done at intervals of 6 minutes/ON and 4 minutes/OFF repeated 6 times.
Going to altitude is as simple as breathing. Typically done while reclining, it is vital that you constantly monitor oxygen levels with the pulse oximeter. Raising or lowering your oxygen levels can be achieved by choosing the correct number of stack mixers with a 20-30 second lag in reading the change on your oximeter.