The last time I talked to anybody at Bristol (inventor of the WSPS) they claimed several hundred "saves". As earlier posters pointed out, it doesn't work every time, but it works often enough to make it a worthwile investment, in my opinion. Bristol is very careful about statements about what wire sizes can be cut, but I have seen multistrand steel structural cables over .5 inch in diameter cut. By the way, the cable is usually not cut clean through. The WSPS notches the cable, and the continuing forward motion of the helicopter yanks on the wire, causing a tension failure at the notch.