Aquatic Life Cartridge Solid Carbon Block Pre-Filter for Aquarium 9 3/4" Standard size cartridge includes dual rubber gaskets to ensure 100% water flow-through Activated Carbon removes chlorine and chloramines from most incoming tap water supplies for up to six months Durable outer and core wrap keeps carbon secure throughout cartridge life 9 3/4" Standard size cartridge includes dual rubber gaskets to ensure 100-percent water flow-through Activated Carbon removes chlorine and chloramines from most incoming tap water supplies for up to six months Durable outer and core wrap keeps carbon secure throughout cartridge life