Wonnv LED Light-up Skateboard Wheels Features :1. 59mm x 45mm standard cruiser wheel size;2. Each colored wheel lights up with pure color as pictures when spinning with high intensity LEDs; 3. No batteries required, light-up by magnetic induction;4. Including ABEC-9 high performance and durability bearings;5. 78A Crystal clear Polyurethane wheels for smooth riding;6. You will receive 4 Pcsï¾ Pre-assembled wheels including magnetic parts and bearings with good package.How it works :The LED wheels do not require batteries, light-up by Magnetic Induction. The interior of the wheel has been equipped with a magnetic parts, which fixed by two bearings. The core of the wheel then spins around this magnetic parts. Basically, the whole unit works like a dynamo that generates the energy used by the LEDs.How to install :ï¾ The LED wheels are easy to install, just simply place the wheels on the axle like regular wheels.Notice: IF the LEDs do not light up, Please tighten the nuts.