If you would like us to fit and install a new Harrison Design rear sight to your slide which is already machined correctly, 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. The fee starts at $55.00 + $25.50 return shipping by USPS, insured for $600, small flat rate box.