Pro-Line pair of aluminum 12mm front clamping hex adapters for the B4.1. If you just converted your B4.1 to 12mm hexes, then Pro-Line’s clamping hexes are a must have for all serious racers. These hexes clamp on to the axle and will not fall off when you change tires like the plastic hexes. The blue anodizing will look trick on your Factory Team kit and features an etched P-L logo so you can show off your love for Pro-Line! These clamping hex adapters are made from high quality, aircraft grade aluminum so you know that they will last and stand up to the power of your B4.1.