I’m right in between a small and medium. I purchased a medium Base Camp Hoodie. I’ve bought medium Endurance Tee shirts from Woolx before and love them. The medium Base Camp Hoodie was just a little big. So, I got online, filled out the return form, printed the label, and dropped it off at the post office. Easiest and most efficient return I have ever done. And it was free. Great customer service and great products.