The Nispira Replacement Filter is designed specifically for Dolphin Robotic Pool Cleaners, such as the Nautilus CC Plus and M400 models. This pack of 4 filters is compatible with Dolphin brand pool cleaners and is suitable for both above ground and in ground pools. The rectangular-shaped filters have dimensions of 10.5" x 6.4" x 0.5" and are made of white material. These filters are lightweight at 1 lb each and provide an effective way to keep your pool water clean and clear.