Run fast, filter faster. The UltraFlask+ Filter Cap threads seamlessly onto all of HydraPak's 42mm running flasks and handhelds for a lightweight, straightforward filtration solution. Featuring a traditional bite valve and cap design, runners can drink freshly filtered water directly through the high-flow Blaster valve. Care: Avoid freezing filter. Freezing may ruin the hollow fiber membrane. If in freezing conditions we recommend you keep the filter in your pocket or near your body to prevent freezing. *Effectively removes common waterborne bacteria, such as E.coli (99.999%) and parasitic cysts (99.9999%) per HSF 42. Included in the package: - 42MM Filter Flask Cap - Bite Valve - BackFlush Adapter - Filter Manual - Basic Care & Use Instructions Specifications: - Cap Size: 42 mm / 1.65 in - Dimensions: 115 mm / 4.5 in - Weight: 36 g / 1.3 oz - Material: Silicone POM, Hollow Fiber, ABS