Box Components Hollow BMX Race StemBy removing the rear pinch bolts and moving the mounting bolts to the middle of the stem, we reduced the weight and size and eliminated a serious hazard to the riders knees. To ensure proper clamping force, the stem must be mounted on a fork with at least 40 millimeters of exposed steerer tube. The BOX Hollow BMX Stems come with a 48 or 53 millimeter extension and a 5 degree rise or drop. ###section### Product Specs TYPE: Front Load REACH: 48 & 53mm