One size fits nobody, two sizes fit all. To make sure you order the right size, you can measure your neck. If you are 38cm/15″ or less, you can order size I. If you measure 38cm/15″ or more, you can order size II. Necks are actually very much alike, no matter your regular size, weight or waist size. However, if you’re more comfortable with a loose fit, you can also order size II. Not sure what model suits you and your wardrobe best? Go for the BOLD COLLAR WHITE. It’s an update for your entire closet! -X-