When preparing the Explorer rebreather you will eventually reach the point where you are prompted to complete a pre-breathe. If you have difficulties getting through the five-minute sequence, try this tip. Begin by exhaling into the counterlungs until full, then start your pre-breathe in a safe seated position. By launching the sequence with “dirty air,” the unit will quickly jump into action to raise the PO2 and you will easily work through the pre-breathe without getting timed-out for inadequate ventilations. If you want to speed up your pre-dive check, add an optional CO2 sensor and watch the sequence shorten to one minute!