Grayl GeoPress One-Way Silicone Valve

This funny looking thing allows you to add sport drink mixes and electrolytes to the clean, purified water coming out of your GeoPress Grayl bottle - without compromising the integrity of the filter. It is made of food-grade silicone. To clean, hand wash the valve with warm soapy water or place in a dishwasher.

Note: only compatible with the 2nd generation cartridges first sold in April 2023 that inclue a new "core" and "flow channel" design (horizontal vents).