Zero means none and so does the Xero 21" boardshort because it has no back seam. Ergonomically enhanced to create superior comfort and flexibility to reach higher performance levels in the water. This top of the line boardshort is like no other. It's designed with our exclusive Platinum X Quad stretch fabric, as well as our PX Infinite seam technology with welded panels. In addition, our repel gel technology minimizes friction and water absorption for a lighter weight fit. Heat transfer detailing appears at the waistband, side seam and side pocket.