The TMC V2 Skim Bubble Stop filters any remaining micro bubbles from the protein skimmer and prevents them from flowing into the aquarium or sump. The V2 Bubble Stop can also be used to provide additional post skimming filtration and the removable sponges mean that it can be incorporated with other filtration components and can be used to house other forms of filtration media such as carbon, using a V2Filter Media Bag provided. To fit the V2 800, 1000 and 1500 skimmers