Alpinestars Boot Smx 1Black 41 3401-0104 The S-MX 1 Boot blends the racing lines of the S-MX racing boot collection with low-cut comfort and convenience. The durable and ultra-light Microfiber upper is reinforced with rugged TPU armor while the shank reinforced sole uses a special rubber formulation for enhanced grip and durability. Construction Upper constructed from lightweight and durable microfiber. Breathable mesh inserts and perforated side panel improve airflow. Plush 3D mesh inner liner offers enhanced comfort and feel.