This is a Rear Fully Adjustable sight, White Outline, for the Colt Pistol Model 1911-A1 style pistols and clones. This sight sits "Low Profile" and made to work with the original front sight on the pistol. The dovetail base width is approximately .330" on this series of sights. If this base is wide for your dovetail you will need the 1911 colt Mil spec 70, 80, 90 series version which is a bit smaller at approximately .322". (We also have these listed for sale). This sight uses the original Colt stock front sight and sits low profile when mounted. Additional wrenches are included in the package. These are LPA brand sights that come from Italy, they are top quality. The rear sight is fully adjustable, for elevation and windage, so you may adjust it in any way to your liking to correct your pistols point of impact. The sight set is made of steel construction, Not plastic. These sights use the original dovetails/slots on the pistol slide. These are the best sights on the market today to improve your pistols sighting. LPA Part Number TPU45CT18.