You won't be disappointed. - Vortex Razor AMG UH-1 Gen II Holographic Sight

Worth every penny. And it's backed by a lifetime warranty. I own many different red dots from many different companies and this model (I own 3) is by far my favorite. Even over the Eotech and Steiner sights I own. Neither of which have a warranty like Vortex.
Not that you'll ever need it, because it's built like a freakin tank. But if you do they will replace it.
If you're on the fence on taking a chance with this sight, get off it! Bite the bullet. Pull the proverbial trigger, man! You will not be disappointed!