The core foam for ZJ paddle blade is the PMI foam, imported from DIAB Group, Sweden (www.diabgroup.com, the best foam in the world, the foam normally is used for making the aircraft) and is shaped by the advanced CNC machine separately for each different blade molds, while most other factories use PU material and shaped by hand. As we all know that the PU foam will re-expansion when in high temperture, that is why the PU foam blade edge will split very easily and the dimpling problem will frequently occur after using for a short time, on the other side, the PMI foam provides ZJ blades with better stability than the PU foam, ZJ Paddle blade seldomly have the split blade edge.