When the light is poor, Nite Ize Seem™ turn bicycle wheels from """"hard to spot"""" to """"impossible to miss."""" Easy to attach and reposition and molded of tough, durable plastic, they're backed with stainless steel clips specially designed to snap securely onto oval, round, and bladed (flat) bicycle spokes. A bright, long-lasting LED (powered by a replaceable lithium battery) is activated by a simple twist, and can be seen in even the darkest night to keep you seen and safe while riding your bike. Not only that - when the wheels are spinning, Seem create the ultra-attention-getting effect of a moving circle of light. Use one or several on each wheel to create your own signature bands of color.