GoTo GEAR has NO affiliation in any manner with, or otherwise endorsed by, Glock, Inc. or Glock Ges.m.b.H. is a complete drop in unit. Special features include a solid one piece stainless steel guide rod precision CNC machined to accept a removable CUSTOM STAINLESS STEEL BLACK COATED, TITANIUM NITRIDE OR STAINLESS STEEL ALLEN HEAD SCREW.