Grayl GeoPRESS Replacement CartridgeReplacement purifier cartridges for GeoPress are designed to last up to 350 cycles (65 gal. 250L). Lifespan will decline when filtering and purifying water with high levels of silt, sediment or tannins. Cartridge press time increases towards the end of the cartridge lifespan; when press time reaches 25 30 seconds, cartridge should be replaced. Cartridge continues to protect, even as press time increases. Compatible with One Way Silicone Valve for