The first internally installed mass damper for mountain bikes made of 97% pure tungsten The TMD reduces vibrations and fatigue in a compact design Aluminum and steel, tapered and 1 1/8" steerers, single and dual crown, oval or cylindrical are all compatible(steerer length of 190mm+ required) IGUS bushings allow the mass to move freely between the 2 springs and are self lubricating Three die spring options are included and calibrated to carefully chosen frequencies(blue-light, yellow-medium and red-heavy) 420g TECH SPECS Model V2 Tuned Mass Damper Description Headtube installed to reduce vibrations and fatigue