"Not as many as you'd think. Once they're incorporated into the isolate matrix, they will flex, stretch and contract according to the movements of the substructure. And depending on how you calibrate them, they'll be transmitting sensory information as well. Temperature and pressure mostly. They'll be impervious to a blade, but sufficient blunt force will damage them. The isolates are incredibly resilient, so you'd be able to take far more damage than a flesh and blood arm, but it's not indestructible. And this design allows the damaged parts to be removed and replaced quickly."