BFG1082 Features: * Filter * One 20-count bag should be used for every 100 u. s. gallons * Grows massive colonies of beneficial bacteria * Provides more growing area than plastic balls, foam or under gravel fillers * Allows best oxygen and water transfer, for best bacterial health * 20 Count Dimensions: * Dimensions: 7.75" H x 6.5" W x 1.5" D