Mike, depends Wich one you're looking at. Some sig p226 are optics ready and some aren't. The ones that are cut for an optic normally use the ROMEO1PRO, Delta Point Pro, and RMR red dot optics cut so you would need to purchase a optics plate adapter separately to add a Holosun or Leopold red dot since they use a different mounting style. If you post again with the model number or upc can give more of a detailed answer. You can find the upc and model number under products description. Hope this helps.

Mike, yes Sir it is with the correct optics plates. Cheers and stay safe! https://chpws.com/product/sig-p226-p229-rx-series-pro-series-axg-scorpion-w-r1p-dpp-cut-w-rmr-holosun-holes-filler-plate-for-trijicon-rmr-sro-holosun-407c-507c-508c-508t/