Big Block Chevy flow pipe is 11″ length and 1.875″O.D.” Tig welded with gloss black finish. This item is used for flow testing exhaust ports on General Motors Big Block Chevy V8 cylinder heads. By testing your exhaust port with and without a pipe you will know how it effects the flow positively or negatively. Flow pipe improves flow roughly 5 percent over an exhaust port with no pipe. Mounting hardware included. Please e-mail with questions.