Articulated Bite Valve w/Magnetic Slider. Pivot valve for quick, one-handed on/off action and magnetic clip to keep valve where you need it. Made from Encapsul material which is a cross modulus blend of “stiff” and “elastic” material for a soft, quiet, clear and rugged reservoir. Super-clean polyethylene encapsulates a flexible core of TPE. Contains Nalgene® AquaguardTM anti-microbial formula which helps prevent growth of bacteria and mold. Stays taste and odor free and aids in the cleaning process. BlackWolf 2 Litre Tank