I'm selling these track spikes because my child's feet have grown too big for them. They're suitable for Ace Shoes and, with the rainy season approaching, could be considered as a second pair. Also, if you're new to track and field, please consider these. Middle school students with less muscle strength may not be able to handle thick-soled spikes. Start with thin-soled ones. Materials: Upper: Synthetic fiber, artificial leather Plate: Synthetic resin Spikes: Metal (iron) = Fixed 3mm and 8mm Suitable Events: For all-weather tracks, 100m-400m, and hurdles Weight: Approximately 160g Sprint Spikes Gender: Men's Type: Spikes #WorldAthleticsChampionships #Sprints #100m #200m #400m #Newcomers