This will allow you to mount your Holosun 507K red dot directly to your Sig P365 slide. This will keep your rear dovetail intact, allowing you to cowitness with iron sights. The top of the base on this red dot is .140" above the top of the slide, so you will need sights at least at that tall to see the sights through the red dot. We recommend a front sight that is .205" tall. The holes will be cut for M4-0.7 to fit the factory screws that came with your red dot. Fitting for length may be required if you are installing the red dot yourself.