These are hand made stainless steel exhaust pipes for 1/10 nitro motors. They have been tested on traxxas. 21 motors they will work on any similar sized 1/10 motors using 1/2 silicone header tubing.
These are NOT for 1/8 big block. I also have one pipe with a spring style coupler fitting (pic 4&5) NOTE the fitment may vary depending what brand header its installed on.