We shot the nickel-cobalt leading edge of an MT Propeller with a .22 rifle. The bullet ricocheted off the nickel edge, only leaving a smudge! MT Composite Propellers are tougher than aluminum blades and stainless leading edge propellers. MT Props are life unlimited. When overhauled, the propellers are brought back to the exact factory new dimensions, unlike metal props. The blades are also field repairable.