Compatible Robots: Polaris 180, 280, 360, 380, 480 Pro, 3900 Sport, compatible with Polaris 91003105 / 9-100-3105 / PP-91003105. Size: Outer Diameter: 4.3 cm; Inner Diameter: 1.4 cm; Length: 7.3 cm Easy to install: Simply replace the worn tail scrubber with a new tail brush at the tail of the hose. EFFECTIVE CLEANING: These filter absorbent sponges contain uniform parallel holes to effectively capture large debris, particles and remove pool cleaners, they also help to scrub the bottom and sides of the pool. Great value for money: 12 x foam brushes, no need to change every week.