Those things don't do much. Anyone who wants your car bad enough can hack through your steering wheel and slide the "club" out through the cut faster than than it takes to break into the steering column to start the car.
I'd look into some kind of PAT (passive anti theft) system like new cars have built in. Basically you keep an RFID tag (or something similar) on your key ring that sends the right code when it's like 6" away from the steering column.
Can't intercept due to the short range and the fact that it only sends a signal when you turn the ignition on and it asks for it, and the number of codes is endless. The car is basically worthless without that tag and without spending the time to smash the car to pieces to locate and disable the PAT system or wenching your car onto a flat bed, there's pretty much no way anyone is getting your car.