I?m 5?7 200lbs, ordered XL and fits perfect. Give it a try if you have the money. Produto ótimo custo benefício excelente entrega super rápida chegou antes da dia combinado These Spenco slippers are awesome. It took me a really long time to find it. Would have given Keens a 5 star if not for the fact that each individual shoe of a pair can differ from one another. I?m not sending it back because I?m not going to pay for the shipping on another piece of footwear, and mostly because I have the Copper Compression High Quality Insoles that I had purchased on Amazon prior to this purchase. I just got it a couple of days ago, and have ran it a couple of times. Make sure everything is tight and fastenes properly. The usb isnt necessary, it only powers the LEDS.