Meet the trainer versatile enough to withstand the rigours of a fast-paced group class or a heavy day in the weight room. Equipped with a flat heel, high-abrasion materials and a flexible sole, it provides comfort and support that's ready to hit the gym. See the specks on the outsole? That means it's constructed with at least 8% Nike Grind material, made from scraps from the footwear-manufacturing process.