Bags lose suction. Bag vacuums rely on the bag to hold back the dust. As soon as dust and dirt enter the bag they start to clog the tiny pores. When the pores are clogged, the airflow is blocked so suction drops rapidly.

Bagless lose suction. Bagless vacuums rely on a filter to hold back the dust, which clogs like a bag. As you use the machine it starts to clog, so you lose suction. Which means, you leave dust behind in your home.

Only Dyson doesn't lose suction! Dyson Root⁸Cyclone™ technology uses 100,000 G of centrifugal force in the cyclones to filter dust and remove dirt from the airflow efficiently. Because there's nothing to obstruct the airflow, it doesn't clog and doesn't lose suction.