Aqueon Replacement Filter Cartridges for QuietFlow Internal Power Filters feature a patented, dual-sided dense-floss design and contain over 25% more activated carbon than competing brands. These cartridges provide even carbon distribution for more thorough filtration and longer effectiveness.Activated carbon and foam filter cartridges for QuietFlow Internal Power FiltersPre-assembled and ready to useProvides highly efficient mechanical and chemical filtrationDirections: For optimal performance and crystal clear water, change cartridge approximately 30 days.

Specifications:
Small:
For QuietFlow models AT10 and AT15
3.38"L x 1.38"W x 5.75"H

Large:
For QuietFlow models AT30 and AT40
4.5"L x 2"W x 5.75"H