***Please read before you make your purchase***EXHAUST DOES NOT WORK ON DURO.M ENGINE 16HP OR 18 HP DO NOT ORDER If you are buying this for a mini bike please be sure to take measure to ensure that you will not burn your leg. Type of material: mild steel, Uncoated Steel. Note:This header does nothave any kind of paint. Tube with 1/16 wall. 2 bolts included and 2 washers. Exhaust has a female thread on the tip that is 1" That does not mean that current measurement is one inch, threads are measured by TPI for thread, read below to understand how threads are measured! -Gasket not included. -Engine not included. This is custom made Header, weighs about 30oz. Center hollow to hollow 2" (please look all The picture for details) Remember this is not a Muffler, is loud! This is not legal for the streets! Reaches a temperature between 200-700F "heavy duty" This been tested on 8HP (301cc) OHV predator, and Predator 13 HP (420cc) engine from harbor freight. -Works also: GX 270 & 389, Briggs 1450 305cc, Lifan LF190F-BQ 15 HP 420cc Made in U.S.A. Finding the Correct Pipe Thread Size National Pipe Threads (NPT) Pipe sizes do refer to physical dimensions, but the plumbing industry standard for the sizes of pipe is not always as straight-forward as measuring the pipe. Measuring the pipe will oftentimes mislead you into choosing the wrong pipe, so do take care. The "pipe thread size" as shown in column 3 of the table below is measured and based on the inside of the pipe. But, to actually determine the size of a pipe, the outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example, a 3/4" NPT pipe thread has an outside diameter of 1.050 inches. Each thread size has a defined number of threads per inch (TPI). The 3/4" NPT pipe thread has 14 threads per inch. Both the TPI (threads per inch) and OD (outside diameter) of the thread are required for positive identification of thread size because several sizes have the same TPI.