Longfield 27-Spline Birfield The Longfield birfields are made out of 100.0 percent chromoly and are precision polished to remove any imperfections that may cause stress risers. The Longfield birfield housing is made out of forged 4340 chromoly steel. The internals of our Longfield birfields are made out of vacuum arc remelted 4340 chromoly steel and then dual heat-treated for superior strength.Specs:
