Worn twice!!! I’m a size 5.5, but I should’ve gotten a 6. They run a bit small :) This shoe has a snug fit; if in-between sizes, consider sizing up. Rebel by name, rebel by nature, the FuelCell Rebel v4 will change the way you look at an everyday trainer. The propulsive feel of FuelCell technology creates a remarkably responsive underfoot that can quickly adapt from long, steady runs to something shorter and more spontaneous. Additional details like a streamlined mesh upper add race-inspired accents to a dynamic upbeat trainer, designed to bring an element of fun back into your run.