Undergravel Filteration Bottom Circular Bar 45.3"x 9.6" Under Gravel Filter Tube Aquarium Features of the Imagitarium Undergravel Filter, 55 Gallon Works freshwater and saltwater tanks Compatible with 55-gallon size tanks connector 16mm .Pipe diameter 22mm.Circular bar tube is 16.6cm , Total 27 tubes.PVC tube is 16.6cm , Total 3 tube Connector L Shape Joint , Total 7 pce