1. These outer sleeves are made of high-quality plastic material to fit your skateboard wheels and prevent them from rolling. This means you can focus on perfecting your technique without worrying about losing your balance or falling off the board. 2. The product has good tensile properties and elongation properties, and is universal for all types of skateboard wheels. Strong grip, stable and more flexible during practice 3. With these wheels, you can practice the moves over and over until you get them right without worry or hesitation. 4. Easy to install and remove, so you can turn it off as needed. 5. Applicable wheels: 49-70mm 6. Weight: 0.1kg