The Katadyn TRK Gravidyn Replacement Element will restore your filter to working order after it chokes to death on an endless supply of pond scum. The field-cleanable .2 micron ceramic depth Gravidyn element will filter up to 13,000 gallons (52,000L) of water, keeping you safely germ-free. Specifications: - Filter Construction: Ceramic - Field Maintainable: Yes - Flow Rate: 1 Gal (4L)/hour - Weight: 1lb 8oz