The spikes are 1-11/16" (1.6875") long in deployed configuration. An o-ring on the spike acts as a lock washer to prevent unintentional loosening, as well as keep soil and (maybe--haven't tried it yet) water out of the threads. Good to have spares in case one falls somewhere you cannot retrieve it. Same for spare feet. Note also that the large diameter of the PMG tripod rubber feet (1.55") acts as a small "snowshoe" to limit the amount the legs sink into soft surfaces, especially after the spike penetrates the surface.