Too many modern mountain bike stems sacrifice strength and torsional stiffness for a few grams of saved weight. The Thomson X4 is the leader in strength and stiffness. The X4 starts life as a one-piece 7000 series extruded billet precision solid block of aluminum. Our vision of the perfect stem… the X4 is the purist combination of strength, weight and CNC precision. Enduro, downhill, track racers; anyone can run the X4 confidently. It's also light enough for cross country, cyclo-cross and road bikes. The Thomson X4 stem allows you to realize the benefits of stiffer forks and bars. X4 offers precise steering, tracking, and more control while riding, all wrapped up in a beautiful design. Pair with our Elite or Masterpiece series posts, a seat post collar and handlebar for the entire cockpit collection.