High Performance - Comfort - Efficiency! Vacuuming has never been easier! With the molded-in ergonomic back rest, these machines are a joy to use. Any vacuum will test to optimum performance when new. The true test of performance comes as debris fills the vacuum bag. In older tubular backpack designs, the bag bulges and stretches when it fills, contacting the side wall and top of the motor, severely reducing airflow. The new HydroForce Back Pack's 3/4" per side increase in diameter and new bag support increase airflow and reduce motor heat, extending the life of the motor and allowing peak performance under all conditions - even when the bag starts to get full.