***Please read before you make your purchase*** 1" Common male Pipe Thread... 1" does not mean the actual size of the outside diameter... read at the bottom of the page to understand how to measure threads, Each thread size has a defined number of threads per inch (TPI). Do you need a muffler? search on amazon for: B0CHR3MCSP Exhaust Pipe 1" Female thread for: Predator 301cc, Predator 420cc, GX Hond_a 240, GX270, GX Hond_a 390 Has a common 1" or what they call a 1" threaded black pipe Female water pipe thread, the thread is 304 stainless steel and is welded to the mild steel tube, see photos for better details. Material: mild steel. Includes hardware & Gasket -Engine / muffler not included Center hollow to hollow can go from 2"- 2.25" This been tested on 8HP (301cc) OHV predator, and Predator 13 HP (420cc) Works also: GX Hond_a GX240, 270 & 390, Briggs 1450 305cc, Lifan LF190F-BQ 15 HP 420cc Works on Duroma_x and predator 459 but the angle would be less inclined. at approximately 3 oclock. Made in U.S.A.