The integrated metal enhancements strengthens the tenon.
Greenline tenon protection
Greenline instruments are made out of a blackwood/Mpingo composite which prevents the instrument from cracking. Greenline instruments are as professional and great as wooden ones. Unfortunately, they come with one weakness, the tenon can break when exposed to a hard hit. This can happen when the instrument hits the floor or a chair.
Lohff & Pfeiffer offers a special tenon enforcement, which prevents this from happening.