Use of other emergency air sources such as octopus second stage, integrated DV/BC inflator units, bailout cylinders etc. also requires the learning of appropriate skills. These procedures are as complex as buddy breathing up to the point of sharing, and the fundamental difference is that the donor and recipient are not required to alternate breathing with a period when no air is available, which can be a big advantage. These alternatives to buddy breathing also require substantial learning and reinforcement to be reliable in a stressful situation.