The Shearwater can be set for 3,4 or 5 minute safety stops or you can set it for adaptive safety stops. They will change to a five minute safety stop if the dive exceeds 100' or if NDL reaches 5 minutes or less. At the safety stop you can indicate by sign language to your buddies that you have 2 more minutes remaining and when it clears give them the signal for all clear which is by sweeping your hand back and forth across your forearm.