The Newton Sir Isaac Guidance Trainer is a great entry-level shoe for those who are just learning natural running, but want to "wean" themselves from the support of a traditional shoe (especially those of you who aren't willing to cut down your mileage during the transition...we get it!). With features to "guide" you toward better form, including firmer lugs so you know you're landing in the right place and functional toe spring to prevent pushing off from your toes (or "toeing" off), these shoes are the perfect "training wheels" for natural running (see our ChiRunning page for more details on natural running training). SIZING: See Proper Foot Placement in Newtons page for important sizing information Please order one-half to one full size larger than your typical shoe size. The ball of your foot must be over the middle of the lugs in order for the technology to work properly. This should result in about a thumb's width between the end of your longest toe and the end of the shoe. Call the store at 413-727-3188 if you need assistance deciding on a size - we're happy to help and can give you an accurate sizing recommendation based on your foot measurements.