If you would like Harrison Design to fit and install a new dovetail front sight in your slide which is already machined correctly for one, this item is for the labor. It covers removal of your old sight, measuring of the dovetail, fitting and installation of your new sight. The new sight is mechanically centered in your slide and is adhered with LocTite 263. If you want your sight drilled for a 1/16" vertical roll pin, it is $10 extra