Package Content: 8 x Replacement Ball Bearings. Please check if your machine model is compatible before purchase so that you can use it better. Stainless steel ball plastic combination bearings, corrosion-resistant materials, professional manufacturing, comparable to the original bearing part, provide smooth rotation and wheel operation. Perfectly compatible with Zodiac Polaris 360, 380, 3900 Sport, ATV (even Vac-Sweep 360, Vac-Sweep 380 pool cleaner models), replaces 9-100-1108. Easy to install, you can do it yourself, replace damaged bearings in time, better protect your equipment and make the machine more efficient. Good material selection, good technology, good product.