This 4" (100mm) hose is super flexible and 3 metres when fully extended, supplied in a 1 metre long box. Because the hose is made from a clear material it provides a visibility that is not found in other types of hose. This clarity allows you to see your system working well or where it may have become clogged, making it a fantastic addition to any dust collection system.Hose diameters are measured internally (to fit over you chosen dust fitting), and sizes are nominal.