You are looking a Aimpoint R-1 that was purchased for around $300 bucks and duracoated Magpul FDE. These sights are the same as the H-1 but come from the afctory silver. Aimpoint has discontinued this sight so you can find them at really good prices. It is mounted to a Larue Tall mount (LT660) that runs $98. Finished product with mount in still $150 cheaper than a stock H-1. This site has seen a few days at the range and the duracoat finish has held up pretty well.
Reticle is alot smaller than pictured.