This stem cap is where your bike fashion sense and the weight weenie in you collide. This Ultralight and ultra-sleek stem cap integrates a 5mm, 10mm or 15mm headset spacer with your stem cap in finely machined piece. Why have extra steerer tube requiring spacers on top of your stem you ask? Well, many carbon steerers require that the steerer tube extend above the stem. Also, riders may want the flexibility to move handlebar height up and down for different types of riding or for bike re-sale. - 1 1/8" top (straight 1 1/8" or 1 1/2" to 1 1/8" taper) steerer tubes only - Light-weight and durable Compatibility - 1 1/8" top (straight 1 1/8" or 1 1/2" to 1 1/8" taper) steerer tubes only