For the compositions of the Butterfly blades I had to make a choice because there are different opinions on the forums.

After several days of research and exchange of information, I chose to use the data of the person whose knowledge and network of professional partners are recognized.

Notice: there is a translation error between the French and English versions on the Donic website.

On the French version of the blades New Impuls, some plies are indicated in "pin" (pine) but on the English version these plies are called spruce. Spruce is épicéa in French. I consider that the English version is the right one and I indicate that these plies are in spruce in my database.