Box One Center Clamp Race StemBox One stems are cold forged from the highest quality 6061 T6 aluminum available. Featuring an open skeletal design and a dual mid bolt wedge mounting system, they are lightweight yet maintain a very high level of strength and stiffness. By removing the rear pinch bolts and moving the mounting bolts to the middle of the stem, Box managed to reduce the weight and size and eliminated a serious hazard to the rider's knees To ensure proper clamping