Pure Hydration TPU Water Reservoir Bladders are manufactured from tough yet strong Thermoplastic Polyurethene (TPU). The large HDPE screw cap allows quick filling with water, whilst the resealing top means that you can fully open it up for a thorough clean. The flexible drinking tube has an insulated & UV protection jacket with an on/off switch & bite valve. These reservoir bladders can be used as a lightweight water carrier, replacements for damaged or old bladders, & a water purifier if used in conjunction with a Pure Hydration inline filter.