Polaris Gray Zipper Double Superbag for 3900 Sport Pool Cleaner 39-310The Polaris 39 310 Superbag is a large, double chambered replacement filtration bag designed specifically for Polaris 3900 Sport or P39 pressure side vac sweep pool cleaners. This gray colored bag expands to hold up to 5 liters of large and small debris within its dual zippered chambers, offering almost twice the debris capacity of a single chamber Polaris bag. It is an original factory replacement part compatible with both Polaris 3900 and 280 pool