Polaris 280 All-Purpose Bag with Zipper Closure for automatic pool cleaners. The bottom measures 3” in diameter and has two "dog-ear" clips with oval shapes on the end of them. The plastic zipper design closes the back of the back. This feature makes the bag extremely easy to clean because debris does not get stuck in it on its way out. The older velcro style will tend to grip dirt, sand, and other small debris, making the closure weaker each time you open and empty the filter bag. Cleaning the new zipper bag is now easier, cleaner and doesn't compromise the closure.