<b>How to choose a perfect size?</b> <br><br> ♥ Its contoured, ergonomic design follows the natural curve of your body, properly supporting your head, neck and shoulders when you sleep on your back or side. Because it’s designed for precise alignment, you must choose the proper size based on your shoulder dimensions and sleeping position.<br><br> ♥ Placing a ruler perpendicular to your neck, measure the distance from the base of the neck to the outside tip of the humerus bone and the “distance” is the pillow height for you. Please choose the smaller size if your measurement falls on the line between two size.<br><br> <b>♥ Warm Prompt:</b><br><br> Getting Acquainted with your new pillow which may feel more firm than expected. We recommend sleeping on it for a few weeks in order to give your pillow a chance to “break-in” to the way you sleep. As with most new purchases, any “new product smell” that you may experience is harmless and will dissipate in a couple of weeks.