Scope of delivery: 8 x replacement ball bearings. Please check if your machine model is compatible before purchasing so that you can use it better. Combination bearings made of stainless steel balls and plastic, corrosion-resistant materials, professional manufacturing, comparable to the original bearing part, ensure smooth rotation and wheel operation. Perfectly compatible with Zodiac Polaris 360, 380, 3900 Sport, ATV (even pool cleaner models Vac-Sweep 360, Vac-Sweep 380), 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.