Why?

Why do we teach air sharing this way? For several reasons — chief among them:

• It gets air to the out-of-air diver faster. Having to hunt for a an alternate-air-source second stage to give to another diver wastes time.
• It works with both conventional “octopus” alternate-air-source second stages and integrated alternate-air-source inflators, such as the SeaQuest Air Source. Thus, students need only learn one procedure that works with any alternate air source configuration.

What’s wrong with the out-of-air diver simply    
taking your alternate-air-source second stage? »