3-1 Alternating (US Patent 6,152,176A - 1998.10.09; Taiwan Utility Model Patent 153420)

3-1 Alternating is a type of alternating that alternates every other 3 air cell during each alternating cycle. In each alternating cycle 33 percent of the mattress is deflated and 66 percent is inflated, therefore the patient is resting on a larger surface area and will be more confortable and feel less of the gaps comparing to 2-1 Alternating. 

2-1 Alternating

2-1 Alternating is a type of alternating that alternates every other air cell during each alternating cycle. In each alternating cycle 50 percent of the mattress is deflated and inflated.