This is a silicone header pipe connector. Also known as coupler tubing. It is 2 inches long and has an inner diameter of 5/8 inches. It also includes to cinch straps to hold it on tight. In general, this will fit a .35 - .91 size engine. heath! 3 Feb 93 Specs: inside diameter- 5/8" outside diameter- 7/8" length- 2" color- grey