High efficiency, about 90%-95% of water and oil can be filtered out(separation). Compatible with many kinds of air pump. Each bag contains 10 carbon rods and 20 filter cotton of spare filters. For a S700 2Liter scuba tank, it needs to be replaced after about 5-6 times of filling;For a 1Liter scuba tank, it needs to be replaced after about 10 times of filling.;For a 0.5Liter mini scuba tank, it needs to be replaced after about 20 times of filling.