Finally I installed the crash bar thanks to a friend with a torque wrench!
I wrote this review on Amazon, I copy and paste it also here. I apologize for the translation from Italian ...
The product corresponds to the description and is a good paramotor both from a technical and aesthetic point of view. Very fast shipping.
The instructions are completely insufficient, there is no indication of the bolt tightening torque, which is fundamental since the assembly requires the replacement of the engine support bolt! I communicated via email with the seller, but did not want to provide me with this data. I find this attitude absurd, as other manufacturers supply all the data. We are talking about a fundamental thing! If I'm wrong to screw that bolt, I compromise the safety of the bike!
I mounted the paramotor safely looking for advice on specialized forums and adopting the same menagerie values as other crash bars, using a torque wrench.