The F-4, 4 inch stabilizer is made from XFactor's a-tech rubber. It is the next generation in sound and vibration dampening, and, the only fully adjustable stabilizer on the market today. There are no steel rods or supports running through the stabilizer to transfer vibration back to your bow. This gives them the ability to dampen 360 degrees. They also incorporate XFactor's patented Shock Block Technology.