Front body not only takes all the stress from the suspension through the strut upper bracket, it also holds the weight of Engine. This result is body flex such as torsion. Okuyama Strut tower bar connects both side of the strut upper bracket to strengthen front part of the body to let suspension work in the exact designed geometry. It also prevent body flex from cornering force. This result in better handling and stability.
Made of Aluminum.
*The attached image is made of aluminum.