SawStop's saws apply a small amount of electric voltage to the blade of the saw. The current through the blade is continuously monitored. If the saw detects a change in this current (as would occur if a hand or other body part came into contact with the blade) an automatic braking system is activated, forcing an aluminum brake block into the blade. The saw stops within five milliseconds, and angular momentum lowers the blade into the table. The operator suffers a small nick instead of an amputation or other more serious injury.[2] The design takes advantage of the difference in "electrical conductivity" (similar to a GFI circuit) between wood and flesh.[3]