The new Box One 31.8 Center Clamp Stem is the lightest weight oversize BMX stem on the market. Box 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, we managed to reduce the weight and size, and eliminated a serious hazard to the rider’s knees. This stem comes with a 53mm or 60mm extension (black only) and can be run with a 5-degree rise, or flipped over with a 5-degree drop. To ensure proper clamping force, the stem must be mounted on a fork with at least 40 millimeters of exposed steerer tube. Please note, this stem is not compatible with carbon fiber steerer tubes.