For speed training. Indoor or outdoor workouts, Functional fitness, weightlifting, running. Lightweight: Updated upper materials with a breathable, durable, one piece construction. Comfort and speed: A powerflow midsole provides lightweight comfort and 10% better shock absorption and 15% better energy return. Flexibility: Meta-flex technology allows natural flexing in the forefoot and the intergrated metcradle lacing system holds your foot secure in the shoe both ensuring the shoe moves naturally with the foot.