What are the key points to have a suitable fixing/connection ?

First, select a clamp type that is suitable for the joint, paying close attention to the following parameters.

•    Clamp material (steel band + rubber insert)
•    Material thickness
•    Material width
•    Operating conditions — temperature, pressure, and other environmental factors

For clamps that will be exposed to very high temperatures, choose special-grade rubber compounds.
If the installation area is prone to corrosion, opting for stainless-steel clamps will extend the service life of the assembly.
Finally, ensure that the mounting-hole diameter is compatible with the bolt size to be used.