Set of 30 threaded tungsten (volfram) studs that will give you the ultimate grip on those really slippery surfaces. Can be mounted on both felt and rubber soles. Tool for easy mounting of the studs is included.
In general, it is heavier to mount the studs into a rubber sole than into a felt sole. You can use an electric drill, but you have to be careful to set it to the lowest speed / low resistance, and check so that the studs do not enter the sole to deep. You screw until you no longer see the thread of the stud, and let the whole top of the stud be exposed. On a rubber sole, it is important that you mount the studs in the thick parts of the pattern, on the ridges. If mounted between the ridges the traction effect will be less, and there is also a small risk that the top of the thread penetrates the sole and can damage the neoprene sock.