This item is the blade for the rear sight assembly supplied by Colt, not a complete sight assembly.
The HD Snake Sight rear notch dimensions have been enlarged to give the sight picture more prominent light bars on each side of the front sight. Changes to increase the notch size allow more daylight into the sight picture, letting the eye more quickly acquire and better focus on the front sight.
The dovetail has been widened to allow fitting to the sight body, to eliminate the factory sight blade's wiggle, so fairly simple fitting is likely necessary. Please read the installation instructions to decide if this job is in your skill set and you have the tools needed to be successful.
The blade height has been increased by .040” which allows a deeper notch by a like amount to give taller light bars.
The notch width has been changed from .130” to .150” to allow more daylight into the sight picture.
The top outside corners have been shaped in a large radius to minimize snagging on garments or cutting hands or holsters.
The blade’s thickness has been increased to improve the crispness of the sight picture and the radius at the bottom of the blade has been enlarged to strengthen the blade.
The dovetail size has been slightly increased to reduce the slop that existed with the original parts.
The set screw has stayed the same size, 4-40" x 1/8" with a .050” hex drive, so it's hex key also works with the front sight. The set screw’s placement has been moved to the center of the of the blade.
NOTE: LocTite 242 (blue) should be applied to the set screw with the tip of a toothpick to prevent loosening, once windage is adjusted.