Pen-Plax AX3 Universal Cartridges Fitting All UG Filters (2 Pack)</br></br><div style="text-align:left"><b>[Product Information]</b><br><ul><li>Ammonia Removing Under gravel Filter Cartridges are made with top quality zeolites which work to eliminate the top fish killer ammonia</li><li>Under gravel Filter Cartridges solve the problem of overfeeding， over-crowding and foul water conditions</li><li>Filter Cartridges fit all Under gravel filters</li><li>Cubes: 0.0007. Weight: 0.2500 lbs</li></ul></div></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br><img src='http://ecx.images-amazon.com/images/I/41dbeoWgRdL.jpg' noproxy></br><img src='http://ecx.images-amazon.com/images/I/41s8Xu0f1GL.jpg' noproxy></br>