Nite Ize See'Ems 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