GTC 440C stainless steel thrust ball bearings caged in stainless steel retainers developed and patented by Gustavo T. Cecchini's GTC Knives to reduce friction and failures, increase opening time and easier cleaning. The 100% stainless steel construction eliminates the problems of other thrust bearings that are not 100% stainless. Install by cutting a pocket, with a counterbore, in both the blade and frame. Use one bearing in blade and one in the frame. Some prefer to cut the pocket in both frames, and not in the blade. This is a good solution when the blade is already hardened.