Chopped carbon or short strand carbon tow

For the brackets: two layers of 3K 2×2 carbon twill with long fiber orientation, parallel too rocket front/back and perpendicular to fin tips. 

Fins bolted to brackets with three stainless steel barrel nuts.

Once assembled onto airframe or directly on motor the whole assembly is also epoxied together.

Strength testing: will be completed once a full modular fin assembly is produced. Also a full MACH 1.9 flight will be performed to test structure in real flight conditions.