TheLeofoto TFN Stainless Steel Arrowhead Spikesensure stability on soft or frozen terrain, so it is a wise precaution to have an extra set around in case they're misplaced. The 3/8"-16 threads smoothly screw into the interchangeable foot sockets and can be tightened with a hex key.
When shooting on location, things often slip out of pockets, get misplaced or damaged. It's always a good idea to keep an extra set of spiked feet handy in case one or all of them go missing. These spiked feet will keep tripods securely planted on soft ground, sand, or snow.