The Polaris 3900 is an all wheel driven cleaner. The Stainless Steel drive chain provides the most reliable and efficient drive transfer available. Wide Trax tires provide superior torque transfer resulting in aggressive wall climbing and 50% more torque drives the cleaner out of tight difficult areas. A 5-liter capacity bag means less cleaning required. Sporty & Sleek body design sets a new standard in the Automatic Pool Cleaner category.