Powerbuilt 648457 Valve Holder Hose For replacement of valve stem seals and springs with cylinder head on engine Pressurizes the cylinder to help hold valves closed with compressed air Flexible 14-in long air hose features 14mm and 18mm stepped fittings with size 0 ring seals for spark plug hole Replace valve stem seals and springs with cylinder head on engine Pressurizes the cylinder to help hold valves closed with compressed air Flexible 14 inch long air hose features 14 millimeter and 18 millimeter stepped fittings with 0 inch ring seals for spark plug hole /4 inch pipe fitting allows connection to air source