I use these with my asp 15s print with at least 50 percent infill 2 mill wall do not scale up for larger engines the PLA is not strong enough I have tried abs and it worse. they are suitable for this engine only so if you use these please take care and make sure you have a good quality print. I have also put in the original design file so you can move to the engine mount holes to suit your cg which is much better than adding lead to balance a plane