You dive your SE7EN with the large counter lungs in order to have a larger breathing loop. After you are comfortable on your SE7EN you realize that you would like more control and would like to get beyond the recreational dive limits. This Manual Injection Pack allows you to manually add DIL or O2 to your breathing loop. This gives you added control over what you are breathing and can assist with buoyancy. Additionally, it gives you the ability to stay at your own set point if something were wrong with your electronics.