 Below the injector is the stripper, which contains rubber pack off elements providing a seal around the tubing to isolate the well's pressure.Below the stripper is the preventer, which provides the ability to cut the coiled tubing pipe and seal the well bore (shear-blind) and hold and seal around the pipe (pipe-slip).Older quad-BOPs have a different ram for each of these functions (blind, shear, pipe, slip).