The Ultimate Direction FlexForm 500 II water bottle offers new ergonomic shape for easy drinking and carrying. The design is comfortable in your hand or against your body. The FlexForm bottle features a pliable plastic body with a soft Silicone push/pull bite valve. A smaller and lighter cap keeps weight low. The Flexform 500 is the optimal bottle for use with the UDs Hydrolight running apparel, Access waistpacks and Fastdraw handhelds. MATERIALS Polyethylene (BPA-Free). WEIGHT 66 g / 2.31 oz. FLUID 500 ml / 16.9 oz.