Part number help

Hi,just wondered if anyone has any idea what this pipe is called and what it's part number is? I've lifted the picture off the net but I've circled the pipe in question. While changing my sparkplugs, I unscrewed the bracket holding pipes/wires and eased it out of the way but in doing so, that pipe came away from where it was connected and it's lost the bit from inside that seals it. :-(