This is a replacement for broken smoke stacks on a G1 Powermaster Optimus Prime. They fit the original holes. You may need to drill the screw holes just a little to make sure the screw goes in smoothly. For the metal versions you will have to tap your own threads for the screws.
As this replaces a part which was easy to break and cause a choking hazard, I will caution you about the same! If the end breaks off it the piece can be a choking hazard, so don't let a little child play with it!