$25 · Woody's Attack Off-road Tire Screws

These are designed for tires for cars and bikes, etc, but you could put them in your shoes or boots too. They are Zinc coated, high grade carbon steel with a brazed carbide insert Here's a link for how ridiculously priced they are, and also info about their applications. http://www.woodystraction.com/tire-screws-off-road-carbide-studs motorbike, ice, snow, grip, traction, stud, studs, tires, dirt bike, bikes, dirt, road, gs, offroad, snow riding, all terrain, atv, utv,