What kind of material is the best for sprinting spikes, soft or hard, please describe

It depends on your level, if the 200 meters within 23 seconds that is the body of the shoe hard, if the results of the general or the body of the shoe soft point it. The insoles are generally air-cushioned, (except for the cheap ones). Nails also depends on your level, the average person's 8 nails. Achievement is good 5 nails, who said there is no 5 nails ah, that China Hukai that five claws shoes is what