PRECISION ENGINEERING: Our 8PCS Cheimaxy Carbon Fiber Headset Spacers are designed with a meticulous 0.1mm variance, ensuring a perfect fit for your bike's headset and maintaining optimal performance without any installation issues UNIVERSAL COMPATIBILITY: These headset spacers fit seamlessly onto any 1 1/8 inch (28.6mm) front stem fork, making them ideal for MTB, BMX, mountain bikes, and road bikes alike. Upgrade your setup with Cheimaxy versatile bike headset spacers CARBON FIBER MATERIAL: These stem gaskets are made of braided carbon fiber, which is high stiffness, high strength and light weight. The matte black appearance of the braided carbon fiber imparts an understated, high-end texture, allowing you to enjoy the perfect combination of aesthetics and functionality DURABLE AND LONG-LASTING: Built to withstand wear and heat, our Bicycle Stem Headset Spacers feature a clean design with no burrs or jagged edges. The flat ports ensure tight top and bottom joints, delivering durability and precision in every ride ADJUSTABLE HEIGHT: Achieve your ideal riding position effortlessly with our 6-size customization option, which includes 21mm, 12mm, 13mm, 15mm, 210mm, and 115mm spacers. Fine-tune your handlebar height with precision down to 1mm for a personalized riding experience Product description How to Accurately Measure Tolerances on Your Headset Spacer Step 1: Tools Ready Use a standard vernier caliper. Wipe the jaws clean to ensure precise measurement. Step 2: Gentle Grip is Key Place the spacer vertically between the caliper jaws. DO: Let the spacer rest naturally without applying hand pressure. DON'T: Squeeze the caliper handle forcefully - this may distort measurements. Pro Tip: The spacer should stay in place with only the caliper's own jaw tension. Step 3: Read Record Check the digital display/scale while maintaining light grip pressure. Normal tolerance range: 0.1mm