Compatible Robots: Polaris 180, 280, 360, 380, 480 Pro, 3900 Sport, Compatible with Polaris 91003105 / 9-100-3105 / PP-91003105 Dimensions: Outer Diameter: 4.3 cm; Inner Diameter: 1.4 cm; Length: 7.3 cm Easy to Install: Simply replace the worn tail cleaner with a new tail brush at the end of the hose. Effective Cleaning: These absorbent filter sponges contain evenly spaced parallel holes to effectively trap large debris, particles and eliminate pool cleaners, they also help scrub the bottom and walls of the pool. Great Value: 12 foam brushes that do not need to be replaced every week.