The Katadyn® Replacement Filter for Pocket will add up to 13,000 gallons (50,000 l) to your Katadyn® Pocket Microfilter™ depending on water quality. Replacement Filter for Pocket will output approximately 1 quart (1 L) per minute. Keep an extra filter on hand to replace broken or used cartridges, or emergency situation where large amounts of contaminated water will need to be filtered for an extended period of time.