How to Interpret Hose & Tube Dash Sizes. People new to hydraulic and pneumatic industries often ask about what is a hose or tube dash size. Simply put, a dash size refers to a diameter of a hose or tube in 1/16 increments. For example, -6 hose would indicate a hose with inside diameter of 6/16 - or 3/8. In another example, a -10 tube would indicate a tube with an outside diameter of 10/16 - or 5/8.