Xcel XFLEX Kids 4/3mm Fullsuit Wetsuit. Description: Kid's XFLEX 4/3mm fullsuit back zip wetsuit. The X-Flex Surf Wetsuit is a lightweight flexible back zipper fullsuit with the upper body and sleeves in snag resistant 300% PLUS stretch UltraStretch Superlite Neoprene. The X Flex is an Engineered fit with pre-bent knees, pre-bent elbows and contoured to fit your body. Comes in All Black & Assorted Colors. Xflex Construction: Upper Body Upper Body and Sleeves constructed with Ultrastretch and Ultrasoft materials. Offset Zipper Double Glued and blindstitched zipper flap and Offset Zipper with Reinforced zipper base. Superlite Neoprene Superlite Nylon 2 neoprene. Pre Bent Arms and Knees For maximum strength and durability